Challenges for Student Satisfaction of Internship Program in Hospitality and Tourism Industry in Vietnam

ABSTRACT

The internship program is the most crucial supplemental training for students in practical skills, knowledge, and attitude necessary to adapt to the changing industrial world of hospitality and tourism. This exploratory study is to investigate the challenges that bachelor students of Hospitality and Tourism Management (H&T) often experience and need to overcome themselves through internship programs at enterprises in hotel, restaurant, travel, and tourism setting in Vietnam. Data from 400 valid answers out of 442 respondents who have experienced their internship programs through direct and online questionnaires was analyzed by SPSS to identify the industry-specific difficulties that trainees must overcome in order to attain satisfaction with the internship term. The results show the main challenges are communication and conduct, working hours, problem-solving skills, self-confidence, supervision, and working environment but physical requirements. The conclusions help not only future student interns for better preparation but also indicate the Hospitality and Tourism Training Schools and industry enterprises the preparedness for students in psychology and skills to experience the most satisfactory and fruitful internship, which plays essential role in attracting talents to remain in H&T industry and mark the effectiveness of university training program.

KEYWORDS:

• Challenge
• internship
• hotel and tourism
• hospitality student
• satisfaction

Introduction

To be students of Hospitality and Tourism (H&T) Management field, all need to undergo an internship program from 2 to 6 months at enterprises in the industry applied on their own or recommended by the academy. The working environment of Vietnam – a country among ten countries possessing highest rate of tourism growth in the last 5 years (Le, 2020) requires students highly on the ability to practice and integrate into the industrial environment, especially environment at well-known brands or chains.

As the tourism industry in Vietnam is still in thirst of high-quality human resources (Nga & Ngan, 2018), the success of a student internship program becomes more important. Besides the support role of educators and employers, the perceptions of students toward the challenges that they themselves should overcome are necessary. “Internship satisfaction” has been designed and involved quantitative method with questionnaire form by Seyitoglu and Yirik (2015) of University Nebraska (which was filled by 305 Turkish tourism faculty students), and before that by other researchers such as in Hongkong (Chen & Shen, 2012) (employed data collection from students at twenty universities) and (Lam & Ching, 2007) (a total of 307 usable questionnaires were returned), etc. According to Seyitoglu and Yirik (2015), internship satisfaction contributes to positive professional development and industrial perception, which is the expectation of both the academy and enterprise. Another study by Hussien and Lopa (2018) on a survey of 100 internship hospitality students in the US., also concludes that interns’ initiative, as well as the academic support and enterprise support, contributes significant contribution to student internship satisfaction. Most of the prior studies have used the quantitative method as the questionnaire for data collection and analysis. Therefore, this study applies mixed methods to heighten and broaden the implication understanding and improving possible support for student internship satisfaction and better career intention in the hospitality industry.

Many papers published though, there are some gaps leading to this research. With the country that English yet to be a second language like Vietnam, the working environment in H&T using English in communication with guests may lead to lack of confidence and limitation in communication of students. While the internship satisfaction marks their growth from academy learning and a good start for future career decision (Tse, 2010), most students admitted that they have some stresses with seemingly simple matter, during the working period till the end of internship because of new environment and arising situations. The pressure of working full-time in a new busy environment, in a professional or branded enterprise brings challenges that students must face right from the time of their entrance interview. Students are required to follow the working schedule and discipline of the corporate and take over the responsibilities of an employee dealing with customers and with deadlines to fulfill. Many students wish if only they had better notion of the challenges and been prepared better they would have caught up the rhythm faster for a more successful internship term.

Secondly, for former internship satisfaction researches, the effect of student career perception, academic support, and enterprise support toward internship satisfaction is also recognized with the individual and organizational challenges, they, however, have a notable lack of exploration on the challenges students need to take efforts better from their side to stay in this industry instead of only expecting from outsiders. Therefore the expectation on pay, commute, and job characteristics (Hussien & Lopa, 2018) are not mentioned in the scaling of this research.

Thirdly, although Chinomona and Surujlal (2012) point out the necessities of student internship programs (e.g., enhancing theoretical knowledge and developing skills and experiences within the H&T settings) for applying proper knowledge, skills, and attitude which has been prepared at school in the previous internship, the number of internship satisfaction studies in the H&T industry is limited. Besides, there have been a lot of studies relevant to internship programs and determinants or satisfaction of students in many countries but there is rarely a study in Vietnam about this, therefore the objective of this research is to identify the challenges at the internship programs for a satisfactory learning and training in Vietnam, for the universities to prepare better their students for this hard period and for the H&T enterprises to share the worries and expectations of the academies and students toward them.

Reviewing the literature, internship satisfaction in recent studies did investigate the expectations of students for the workplace and the support of tourism school and business. The challenges that most students face consist of both individual and organizational ones, which are communication and conduct, health, problem-solving skills (Lam & Ching, 2007), self-confidence (Chen & Shen, 2012), supervision, working hours, and working environment (Lam & Ching, 2007). These are the challenges which requires the efforts both from the students and from the stake holders. Taking those issues, this research goes from the very first step through the whole process of internship to work out the scaling by the face-to-face survey of core group of samples for the questionnaire on each variable mentioned by other former researchers. Thus, this research is in pursuit of the concrete results which facilitate more effective support from the part of the training and business enterprises in conducting future workshops on skills for students. With the mixed methods, respondents collected to be around 442 samples from H&T of 04 universities in Vietnam context, the data will be analyzed its exploratory factor analysis by SPSS which describe the methodology and the data analysis.

Thus, this study aims to explore the impacts of difficulties in practices on hospitality and tourism student internship and to answer two research questions to fill the research gaps above:

RQ1: Are there any effects of individual and organizational challenges on internship satisfaction in hospitality and tourism enterprises?

RQ2: To what extend does internship satisfaction effect the student career perception, academic support, and enterprise support?

The result of challenges which students should overcome to get satisfaction will also help to improve student career perception, the effectiveness of university training program, and will also maintain talents for this demanding hospitality industry. This study, though, will not detect all the determinants to bring satisfaction to students to avoid subjective expectations out of the ability reach of each student, it is rather to help students realize challenges that they themselves need to prepare and overcome.

Literature review

A proposed model and its research hypotheses

To pursue a quality tourism internship program, relevant partners must always ask the following questions: How is the overall evaluation of students on internship satisfaction? What are the students’ career perceptions after the internship? What have been the individual challenges that the students themselves have overcome during their internship to reach a satisfactory result? What are the organizational challenges? What are students’ expectations from the academy and enterprise support? Although a number of studies in the literature emphasize student internship experiences, there are not many focusing on internship in the Vietnam context.

The objectives of the study were twofold: firstly, to investigate the challenges that the students must overcome during their internships; secondly to identify according to students ‘expectation what support the school and the business can render to help them gain an internship satisfaction. The current research proposes and tests a conceptual model of the challenges influencing hospitality interns’ satisfaction in Vietnam. The proposed model was drawn and developed from previous literatures i.e., (Chen & Shen, 2012), (Lam & Ching, 2007), & (Hussien & Lopa, 2018). The proposed model includes ten constructs that are individual challenges (04 independent variables); organizational challenges (03 independent variables); student internship satisfaction; student career perceptions; academic support; and enterprise support. With the focus only on challenges that students need to take efforts from their sides instead of expecting from other stake holders, and the research is on challenges not on student expectations we leave the expectation on pay, commute, and job characteristics (Hussien & Lopa, 2018) out of the scaling of this research.The proposed conceptual model is illustrated in Figure 1. The following sections explain each factor and its relationship with interns’ satisfaction.

Figure 1. Conceptual model of student satisfaction.

Source: authors’ own contribution.

Background of internship and its roles in tourism education

Various findings have been obtained in some studies conducted in the literature about the internship and its important roles in tourism education (Barron & Maxwell, 1993; Collins, 2002; Walo, 2001; Zopiatis & Theocharous, 2013).

According to Sir E.M Statler (1863–1928), the father of the American hotel, who emphasized the need for hospitality students to experience the demands of management in the real world via a “hands-on” learning experience (Cited from Zopiatis, 2007).

The internship then is defined in some meanings such as work placements, industry work experience, practicum, work integrated education. Davies (1990) states that internship is a kind of experiential learning where students take the opportunity to apply learned theories from schools in real-world situations, and it provides an opportunity for students to integrate and consolidate thinking and action. McMahon and Quinn (1995) called internship a ‘supervised work experience’ and that students are under special guidelines and attention during their internship instead of working alone by themselves in the industry. It is also considered as an opportunity to close the gap between university-learned theory and practical reality, or different perception from student-educator-employer (Yiu & Law, 2012). According to (Walo, 2001), internships constitute an important path to increase students’ learning capacities by providing them an efficient way of learning through active participation in various ways such as seeing, hearing, and doing (Walo, 2001).

Furthermore, the internship is to give students the opportunities to put their knowledge into practice and to provide them some real experience in the job market. As one of the key roles of tourism education is integrating action-oriented learning into the theoretical program, a certain length of an internship period requires to be placed in the tourism curriculum.

To sum it up, internship could be included a three-way partnership between students, institution of education, and the enterprise which accepts the interns (Inkster & Ross, 1998). Zopiatis and Theocharous (2013) highlighted the benefits of a normal internship for these three parties to enhance student intentions in H&T industry after graduation (Zopiatis and Theocharous, 2013). Students gain the experience of the real world. Academic institutions increase its reputation. Employers have the opportunities to recruit and train their potential staff. Tourism internships provide a beneficial experience for all the students, employers, and educational institutions involved.

Internship expectations and perceptions

An internship can be considered as one of the positive strategies for the schools to compete for a larger intake of students by promoting a comprehensive curriculum with an attractive internship program (Lam & Ching, 2007). According to Silva et al. (2016), internships can be used as a successful strategy to bridge theoretical knowledge and practice and enhance graduate employability. After completing their internships, there is a vast improvement in students’ ability and confidence to work with people, their knowledge of how the industry works, their ability to adapt to changes, their leadership, and their financial management competency (Lam & Ching, 2007). Zopiatis (2007) defined that internships provide an opportunity for students to apply classroom theories to practical issues in the actual business setting, and most importantly to evaluate whether their career choice is compatible with their interests and personality. Internships are especially helpful for resourceful students who want to gain some practical experience about the work by working in a real business environment. Internships also provide the students with the necessary skills to be effective in the work environment (Chinomona & Surujlal, 2012). They give the young candidates the opportunity to practice their theoretical knowledge and develop their skills and experiences within the sector (Bogdana et al., 2012).

Besides, internships also help students increase their self-confidence and exposure to whether their career choice is compatible with their interests and personality (Dobratz et al., 2014). Cook et al. (2004) agree that internships aid students to gain confidence in finding employment upon graduation from college. Students become more self-assured when looking for work than before because they have had real-world practice in their industry added to their university education (Simmons, 2006). Also, industry professionals and institutions benefit by providing internship experiences (Cook et al., 2004).

Students benefited from the time spent on an internship as they have gained transferable skills, enhanced their understanding of their choice, and provided a concrete link between theory and application (Bullock et al., 2009). As internships play a major role within the higher educational environment, potentially impacting students’ career perceptions and aspirations, there is a change in students’ perception of hospitality employment post-internship and how this impact on future career intentions from a developing country’s perspective.

Nevertheless, the provision of any experiential learning activity, such as a hospitality internship, does not necessarily provide a meaningful learning experience (Zopiatis, 2007). The most common factors that create negative perception of interns are found to be little or no pay, weak employee–supervisor relations, poor communication, lack of coordination and disorganized work environment, limited or no delegation, long working hours, and overall a hectic working environment (Collins, 2002; Lam & Ching, 2007). It is also argued that educational institutes fail to prepare students adequately in order to cope with the challenges and demands of work in this sector (Lam & Ching, 2007).

As a result, a considerable number of graduates decide to seek employment in other sectors (Barron, 2008; Jenkins, 2001; Zopiatis, 2007). Students’ experiences from their internship participation may be positive or negative depending on a number of moderating factors and their expectations (Marinakou & Giousmpasoglou, 2013).

The individual challenges

Self-confidence

The main purpose of the tourism internship programs is to prepare the students to be good implementers in real life, taking good decisions with the theoretical foundations they established during their study. Many students expect to increase their own confidence after completing their internships because self-confidence will bring them more opportunities to have new experiences. During the internships, hospitality students often are placed in positions that require them to interact with guests directly, i.e., servers, front desk staff in hotels which may cause stress to them from the first days (Lam & Ching, 2007). It will be worse if they are given positions in this field involving tasks with certain responsibility, or they receive insufficient training because of high season and the limited period of the internship. Therefore, the higher the self-confidence preparation of interns, the higher levels of internship satisfaction as the proposed hypothesis below

H1: Self-confidence is positively related to internship satisfaction

Communication and conduct

For many students, effective communication skills are not their gift. Yet, in working environment, communication and conduct are of a higher level, that is professional. Unable to “fit” into the organization’ s culture seems to be another concern where students find themselves having difficult in communicating and building good relationships with colleagues (McMahon & Quinn, 1995). In addition, having social experiences with coworkers or supervisors during the internship is a great chance that may enhance interns’ interest in and excitement regarding working (Hussien & Lopa, 2018). So, we hypothesize the relationship of student internship satisfaction with communication and conduct at the workplace as below

H2: Communication & Conduct is positively related to internship satisfaction

Health

Lack of training physically and being illusioned by the gaudy appearance, students take employment conditions in the tourism sector as too hard with late working hours and long-standing shifts compared to other sectors, therefore high turnover rate is a result (Davidson et al., 2006; Fox, 2001; Richardson, 2008; Teng, 2008). Students who had bad internship experiences with running errands on motorbikes or with being carsick also leaving the sector due to the not meeting the working conditions and due to the limitations on improvement opportunities. The association of internship satisfaction and trainee’s health/physical condition is looked through as the below hypothesis

H3: Health is positively related to internship satisfaction

Problem solving skills

The main purposes of internship is to help students to develop their thinking, problem-solving, and communicating skills which are considered critical elements of a good education by providing them a real-world experience. In their study findings, Hussien and Lopa (2018) employed an online questionnaire to 100 hospitality students who have joined internship program. The SEM outputs suggested academic preparedness, student self-initiatives, skills variety are crucial factors to lead to internship satisfaction. It also mentioned site supervisor should give interns an opportunity to carry out the work by themselves and to do different job tasks using a variety of their skills and talent. These opportunities can enhance the skills that they are going to need to solve problems and contingencies at their working environment. Consequently, we hypothesize that:

H4: Problem solving skills is positively related to internship satisfaction

Organizational challenges

Supervision

One of the hardest challenges the sector is facing is to create certain methods to attract the skillful people and to retain them. Consideration and support of direct supervision in assigning work, mentoring and creating opportunities to interns are very important. Some employers may not be fully aware of internship objectives or may treat interns as a supplement for a labor shortage. As mentioned by Fox (2001), instead of developing potential employees through internship, many companies would only allocate people in particular areas where they need someone. Some companies may even be uncertain of what to expect from students, how to train students successfully and what skill levels students should obtain during their internship period (Huyton, 1991). To assess the impact of supervision role on student overall satisfaction, Lam and Ching (2007) conducted a quantitative research through 307 valid questionnaires. The outputs show supervisor, team spirit, and especially help from supervisor led to student overall satisfaction. Therefore, the degree of supervision consideration on interns would affect the internship satisfaction like below hypothesis:

H5: Supervision is positively related to internship satisfaction

Working hours

Specialized working condition in the hotel and tourism industry is to deal with different customer and task in long hours or night shifts. Besides, Robinson and his coauthors conducted qualitative study through 34 students in hospitality in Australia in 2009 and 2010 investigating student career choices and goals after attending the internship terms. The results show it is tough to work with longer hours, longer shifts but lower wages, compared to other operation settings (Robinson et al., 2015). Consequently, it occurs the higher turnover rate which decreases the internship satisfaction and job opportunities and retention (Lam & Ching, 2007), as below hypothesis:

H6: Working hours is positively related to internship satisfaction

Working environment

Eventually, the industry faces a challenge in positioning as a more attractive career option in the eyes of youth as only around half of the tourism and hospitality and management graduates opt to be employed in hospitality positions (King et al., 2003). Despite the offering of full or limited-service properties, the working environment and working colleagues play the role of enterprise in internship satisfaction. In addition, Robinson et al. (2015) confirmed the relationship of student internship satisfaction with working environment as team spirit and autonomy. Therefore, we hypothesize that:

H7: Working environment is positively related to internship satisfaction

Student career perception

The benefits of internship terms obviously play a crucial in enhancing student career perception as students could improve their competencies and confidence to deal with people, with complicated works, and especially their personal financial management (Lam & Ching, 2007). The complicated working conditions and challenging working experience best help interns for their career choice (Zopiatis & Theocharous, 2013), (Chinomona & Surujlal, 2012). Using structure equation model (SEM) through 400 samples in Cyprus, Zopiatis and Theocharous (2013) highlighted the impact of students practice toward student intention to go further with hospitality careers even though they can work later with other industries as well based on their interests and personality. On the downside, the poor preparation from both students and educational institutes (Lam & Ching, 2007), ineffective communication, unattractive working environment with long working hours may negatively affect the perception of interns (Yiu & Law, 2012), and (Collins, 2002). Seyitoglu and Yirik (2015) examined the degree of 305 student perception on the internship. It confirmed the impact of the tourism educators, professional development on industrial perception of the students. Therefore, internship satisfaction has a close relationship with student career perception as followed hypothesis.

H8: Internship satisfaction is positively related to Student career perceptions

Academic support

Seyitoglu and Yirik (2015) involved a questionnaire to 305 tourism faculty students in Turkey to determine the internship satisfaction toward the tourism educators, and professional development. The results mention internship satisfaction helps the educational enterprises build in students the professional development and industrial perception (Seyitoglu & Yirik, 2015). Besides, Hussien and Lopa (2018) examined interns’ initiative basing on the academic support. It is also argued that educational institutes fail to prepare students adequately in order to cope with the challenges and demands of work in this sector (Lam & Ching, 2007). It is thus crucial to explore the gaps of educators (Yiu & Law, 2012) to increase the significant effects on student internship satisfaction as below hypothesis

H9: Internship satisfaction is positively related to s Academic support

Enterprise support

To fulfill the endless high qualified applicants in the travel and hospitality in Vietnam, enterprise support earns its contribution (Nga & Ngan, 2018). The considerable freshmen seek employment in this setting from internship terms to permanent jobs (Barron, 2008; Jenkins, 2001; Zopiatis, 2007). Throughout the internship participation, students gain from positive or negative experiences relating to moderating factors and their expectations (Marinakou & Giousmpasoglou, 2013). It is therefore important to dig out for practitioners/employers (Yiu & Law, 2012) to tackle the changes require and to increase the retention rate of high qualification students in the industry by the below hypothesis

H10: Internship satisfaction is positively related to Enterprise support

Conceptual model and hypothesis

In the research of Today’s intern, tomorrow’s practitioner? – The influence of internship programmes on students’career development in the Hospitality Industry, Chen and Shen (2012) did prove their model of industry involvement including fair working environment and training as well as personal commitment with dedication to work and learning are essential determinants to students’ satisfaction. What is more, the support from Hospitality Industry and schools are factors to decide student career development in the industry. That is why we construct H7 (working environment) to be the variable and H8, H9, and H10 in the model to be what support students expect from their academy and internship organization. In their research, Lam and Ching (2007) again cited personal challenges for students to be problem-solving ability and the organizational challenges to be supervisor’s support, working hours which are our H4, H5, H6 in the model. The model of Hussien and Lopa (2018) which divides individual and organizational environment is suitable to our research. However, for this study after years of watching and interviewing the interns in Vietnam about their personal challenges, the researchers find out three more factors H1, H2, H3 which may not be an issue at other parts of the world but students in Vietnam mentioned them to be their challenges: Self-confidence, Communication and Health/Physical requirements. The proposed model of student internship satisfaction is as shown in Figure 1:

• H1: Self-confidence is positively related to internship satisfaction

• H2: Communication & Conduct is positively related to internship satisfaction

• H3: Health is positively related to internship satisfaction

• H4: Problem-solving skill is positively related to internship satisfaction

• H5: Supervision is positively related to internship satisfaction

• H6: Working hour is positively related to internship satisfaction

• H7: Working environment is positively related to internship satisfaction

• H8: Internship satisfaction is positively related to Student career perceptions

• H9: Internship satisfaction is positively related to Academic support

• H10: Internship satisfaction is positively related to Enterprise support

Methodology

Those research gaps were carried out by mixed methods in term of hotel and tourism cases. The first objective of this study (to identify internship challenging dimensions which drive student satisfaction) analyzed through qualitative and mainly quantitative approaches. Then, the second objective (to increase student internship satisfaction in the future by increasing student perception, academic support, and enterprise support in the long run) completed through the literature review with quantitative method by testing hypotheses.

As for the respondents, we chose participants working in travel and tourism companies, from 3–5-star hotels in Vietnam, and other countries. As the economic to luxury hospitality and tourism concerns are highlighted, where they have engagements in standard operation policies with the emphasis on intern competency and efficiency (Jiang et al., 2012). Respondents must have at least two-month working-experience in their internship programs. The reason is that they need to understand the standard requirements and grasp used policy practices in the workplace. Thus, trainees working at departments such as Housekeeping, Food & Beverage, Front office, Administration (or HR), Customer service, Inbound, Outbound, etc. are objectives of this research for collecting data.

Firstly, the below open-questions were used to recall 05 students’ responses who experienced the internship in hotel and tourism organizations. One-hour interview for each stratified respondent was carried out for screening the main dimensions before conducting other subsequent steps. The qualitative data collection helped the researchers to form the questionnaire as the measurement of all variables reflected in the conceptualization which serve as a tool to collect primary data for this study

1. How is the overall evaluation of students on internship satisfaction?

2. What are the students ‘career perceptions after the internship?

3. What have been the individual challenges that the students themselves have overcome during their internship to reach a satisfactory result?

4. What are the organizational challenges?

5. What are students’ expectations from the academy and enterprise support?

Next, to explore sample’s characteristic and behavior, a quantitative method was applied (Creswell, 2003). Thus, as our research aims to infer the effects of challenging training on student internship satisfaction in the hotel and travel industry, and consequently impacts student career perception then finds out possible supports from institution and enterprises, this approach is suitable to utilize. Therefore, a survey strategy was taken to apply the quantitative data collection and evaluating the relationships between variables (Saunders et al., 2009).

After forming the conceptual framework based on the original primary data collection, the questionnaire technique was used to collect quantitative data. Minor revisions were modified by their in-depth interviews and comments. Then a Pilot test (n = 30) was used to make sure that our constructs are consistent. Consequently, the original statements were modified to finalize the questionnaire. At first, almost 2,000 available students who are in the year intake of 2016, 2017, and 2018 were contacted to fulfill the survey. The data were collected by using the online approach (links spread on Facebook account and e-mail invitation) and offline approach within approximately 10 minutes each (face-to-face with internship students) with stratified samples during May–December, 2020. In total, 442 internship students were contacted successfully, approximately 22.1% response rate. After considering 442 received questionnaires, 400 valid questionnaires were used for the quantitative analysis due to the missing data. The sample size for regression analysis should be 10−15 individuals or more for each independent variable (Halinski, 1970). This study has seven independent variables. As for this exploratory research, the factor analysis is employed, hence it should be more than 200 (Comrey & Lee, 1992). Thus, the sample size of 400 is appropriate for this study.

The questionnaire was prepared in Vietnamese then translated into English. The pilot test was conducted in April 2020 after accumulated direct interviews with a focus group of students on the challenges after their internship in H&T. The scaling for each issues was made from these interview. From May, 2020 till December 2020 was the time to collect data through the system of getting internship feedback of Hoa Sen University and other Universities which have H&T faculty. The conducted qualitative and qualitative content based on the similar sample selected for the survey. In order to study thoroughly all the dimensions of each challenges, a questionnaire of six parts has been designed. The first part to be the conditions necessary to participate in this survey with question to know respondents to have taken an internship (i.e., Have you spent a complete internship in a hospitality and/or tourism enterprise?) to avoid inappropriate samples. If there are relevant respondents, the subsequent questions in the second part takes information as how long, in which enterprise (restaurant, hotel, or travel company), name of the enterprise, the location, and job position. The third part focuses on four variables of individual challenges in the model and the fourth part on variables of organizational challenges. The fifth part is to ask for the evaluation of students on the impact of each variables on the Table 1 satisfaction during the internship. The sixth part is to know what they gain or feel satisfied in their internship. The seventh is their expectations of suggestions to the academy and enterprise for supporting a better internship. The last part is to take personal information of students such as name, DOB, gender, university, major and faculty. Hereunder is the table of variables and measurements in detail:

Table 1. Key references of construct based on prior studies.

Variables	Measurements & Coding	References
Self-confidence (SC) Questions to ask if students feel lack of confidence in these situations	SC 1_Before the job interview	(Chen & Shen, 2012)
	SC 2_When getting to know the new environment	(Chen & Shen, 2012)
	SC 3_When introducing to people	(Lam & Ching, 2007)
	SC 4_When communicating with people	(Chen & Shen, 2012)
	SC 5_When being assigned a new task	(Lam & Ching, 2007)
	SC 6_With own knowledge	(Chen & Shen, 2012)
	SC 7_With own skills	(Chen & Shen, 2012)
	SC 8_With foreign language abilities	(Chen & Shen, 2012)
	SC 9_When working alone	(Lam & Ching, 2007)
	SC 10_When working with other colleagues	(Chen & Shen, 2012)
	SC 11_When handling situations	(Robinson et al., 2015)
	SC 12_In communicating with guests	(Lam & Ching, 2007)
	Communication and conduct (CC) Questions to find if they have difficulties in these situations	CC 1_Talk and communicate with senior management	(Lam & Ching, 2007)
CC 2_Talk and communicate with direct manager		(Robinson et al., 2015)
CC 3_Talk and communicate with colleagues		(Robinson et al., 2015)
CC 4_Talk and communicate with guests		(Robinson et al., 2015)
CC 5_Behave when witnessing former employees doing the wrong workflow		(Seyitoglu & Yirik, 2015)
CC 6_Behave when facing some managerial behavior		(Seyitoglu & Yirik, 2015)
CC 7_Talk and communicate with guests in an appropriate way		(Robinson et al., 2015)
Health/Physical requirements (PR) Questions to know which physical requirements that students take it to be tough		PR 1_Stand continuously for a long time	(Chen & Shen, 2012)
	PR 2_Stay up late for the work shift	(Chen & Shen, 2012)
	PR 3_Move around by personal vehicles	(Chen & Shen, 2012)
	PR 4_Travel in tour vehicles (minibus, bus) -> for car-sick students	Developed from in-depth’s interview
	PR 5_Carry heavy things	Developed from in-depth’s interview
	PR 6_Be in constant contact with chemicals	Developed from in-depth’s interview
	Problem-solving skills (PSS) Questions to know which skills they are facing difficulties	PSS 1_Listening	(Lam & Ching, 2007)
PSS 2_Keeping calm		(Hussien & Lopa, 2018),
PSS 3_Presenting the incident		(Raymond & McNabb, 1993)
PSS 4_Empathy		(Hussien & Lopa, 2018)
PSS 5_Identifying the problem		(Hussien & Lopa, 2018)
PSS 6_Analyzing, evaluating the problem		(Raymond & McNabb, 1993)
PSS 7_Working out solution alternatives		(Raymond & McNabb, 1993)
PSS 8_Choosing the appropriate solution		(Raymond & McNabb, 1993)
PSS 9_Carrying out the solution		(Raymond & McNabb, 1993)
PSS 10_Following up/Report		(Raymond & McNabb, 1993)
Supervision (DFS) Questions to cover all difficulties may occur in enterprises relevant to supervision	DFS 1_The manager did not care in the internship	(Zopiatis & Theocharous, 2013)
	DFS 2_The manager did not give an instructions/training	(Zopiatis & Theocharous, 2013)
	DFS 3_The manager assigned a lot of work	(Zopiatis & Theocharous, 2013)
	DFS 4_The manager assigned overlapping work with others	Developed from in-depth’s interview
	DFS 5_The manager could not control his/her temper	Developed from in-depth’s interview
	DFS 6_The manager assigned unappropriated work	Developed from in-depth’s interview
	DFS 7_The manager set too many rules which limited your abilities	Developed from in-depth’s interview
	DFS 8_The manager did not assign any work	Developed from in-depth’s interview
Working hour (WH) Characteristics of career that some students feel difficult to their own conditions	WH 1_Must be on time always	(Robinson et al., 2015)
	WH 2_Finish works late (after 10PM)	(Lam & Ching, 2007)
	WH 3_Must work overtime often	Developed from in-depth’s interview
	WH 4_Have to work in night shift	Developed from in-depth’s interview
	WH 5_Must work in broken shift	Developed from in-depth’s interview
	WH 6_Must work on holidays, New Year	Developed from in-depth’s interview
Working environment (WE) Questions on the challenges in working environment	WE 1_Colleagues are unfriendly	(Robinson et al., 2015)
	WE 2_Colleagues did not share any experiences	Developed from in-depth’s interview
	WE 3_Colleagues made students do all the work	Developed from in-depth’s interview
	WE 4_The working environment was very pressured	(Lam & Ching, 2007)
	WE 5_The working environment required above your ability	(Lam & Ching, 2007)
	WE 6_The enterprise culture is so different	(Chen & Shen, 2012)
Internship satisfaction (IS)	IS 1_Confidence	(Chen & Shen, 2012)
	IS 2_Communication and conduct	(Lam & Ching, 2007)
	IS 3_Health	(Chen & Shen, 2012)
	IS 4_Problem-solving ability	(Hussien & Lopa, 2018)
	IS 5_Supervision	(Zopiatis & Theocharous, 2013)
	IS 6_Working hours	(Robinson et al., 2015)
	IS 7_Working environment	(Robinson et al., 2015)
Student career perception (CP)	CP 1_Perceive clearly about future career	(Lu & Yirik, 2014)
	CP 2_Perceive clearly about job requirements	(Lu & Yirik, 2014)
	CP 3_Apply what have been learned	(Robinson et al., 2015)
	CP 4_Learn new things	(Robinson et al., 2015)
	CP 5_Do new things	(Robinson et al., 2015)
	CP 6_Improve communication skill	(Lam & Ching, 2007)
	CP 7_Improve operating skill	(Lam & Ching, 2007)
	CP 8_Enlarge relationships	(Stansbie & Nash, 2016)
	CP 9_Increase self-confidence	(Chen & Shen, 2012)
	CP 10_Improve problem-solving skill	(Chen & Shen, 2012)
	CP 11_Gain self-development	(Zopiatis & Theocharous, 2013)
	CP 12_Gain self-completion	(Zopiatis & Theocharous, 2013)
	CP 13_Perceive own contribution	(Yiu & Law, 2012)
	CP 14_Satisfy with career choice	(Yiu & Law, 2012)
	CP 15_Recognize future career path	(Yiu & Law, 2012)
Academy support (AS) The workshop on soft skills that the academy can perform	AS 1_Organizing workshop on how to improve self-confidence	(Lu & Yirik, 2014)
	AS 2_Organizing workshop on how to improve communication skill	(Lu & Yirik, 2014)
	AS 3_Organizing workshop for alumni to share their experiences	(Stansbie & Nash, 2016)
	AS 4_Surveying students’ wishes/expectations before the internship	(Zopiatis & Theocharous, 2013)
Enterprise support (ES) The necessary preparation	ES 1_Assign work in accordance with your wishes	(Zopiatis & Theocharous, 2013)
	ES 2_Assign work in accordance with your health	(Stansbie & Nash, 2016)
	ES 3_Assign work appropriately	(Zopiatis & Theocharous, 2013)
	ES 4_Assign internship mentor	(Zopiatis & Theocharous, 2013)
	ES 5_Facilitate integration of corporate culture	(Yiu & Law, 2012)
	ES 6_Create opportunities for self-development	Developed from in-depth’s interview

Source: authors’ own contribution.

The questionnaire included 08 parts. The sample’s demographic is shown in Table 2, such as personal information (female: 69.5%, male: 30.5%). The majority respondents are from Hoa Sen University (66%), followed as Hutech (21.5%), Van Lang (12%), Hong Bang (0.5%). And samples’ majors are in discipline of hotel (42.3%), tourism (33.35), restaurant (22%), and management (2.5%). The internship duration comes from 2 months (47%), 4 months (39.5%), 6 months (11.5%), to 12 months (2%). The venues are mostly in HCMC (92.5%), followed by Middle cities, i.e., Nha trang, Da nang (2.5%), Provinces, i.e., Binh duong, Dong Nai, Vung Tau (2%), overseas countries, i.e., Hong Kong, Bhutan, Miami, Florida (2%), and at islands as Phu Quoc, Con Dao (1%). The working placement closely relates to tourism, hotel, restaurant, and mixed enterprises at 32.8%, 29.5%, 24.3%, and 13.5%, respectively. The respondents experienced in different departments in the enterprises from year 2018 to 2020, i.e., Hotel operation (Front Office, Housekeeping, Food&Beverage, Event), Tourism operation (Inbound, Outbound, Tour guide), Sale & Marketing, Admin (Human Resource, Accounting, Customer service), and others at 57.3%, 17.5%, 13.8%, 10%, 1.5%, respectively.

Table 2. Demographic profile of respondents.

Items	Description	Percent
Gender	Male	30.5
	Female	69.5
University	Hoa Sen	66.0
	Hutech	21.5
	Van Lang	12.0
	Hong Bang	.5
Major	Tourism	33.3
	Restaurant	22.0
	Hotel	42.3
	Management	2.5
Duration	2 months	47.0
	4 months	39.5
	6 months	11.5
	12 months	2.0
Organization	Tourism	32.8
	Restaurant	24.3
	Hotel	29.5
	Tourism & Hospitality	13.5
Location	HCMC	92.5
	Provinces (Binh duong, Dong Nai, Vung Tau)	2.0
	City in Middle (Nha trang, Da nang)	2.5
	Island (Phu Quoc, Con Dao)	1.0
	Overseas (Hongkong, Bhutan, Miami, Florida)	2.0
Department	Hotel operation (FO, HSK, F&B, Event)	57.3
	Tourism operation (Inbound, Outbound, Tour guide)	17.5
	Sale & Marketing	13.8
	Admin (HR, Accounting, Customer service, Service)	10.0
	Others	1.5
Intern year	2020	56.8
	2019	33.8
	2018 and before	9.5

Source: authors’ own contribution.

To explore the student internship’s challenging factors, satisfaction levels, career perception, and support of institution and business as results, 87 scaling questions in a five-point Likert scale (1. Strongly Disagree, 2. Disagree, 3. Neutral, 4. Agree, 5. Strongly Agree) were carried out through restricted samples in cross-sectional data.

The common method bias or common method variance (CMV) is a normal issue in quantitative approach when the data were conducted from only one source. Therefore, we tested CMV issue based on Harman’s one-factor test (Podsakoff, 2003) to minimize the error terms. The cumulative percentage of total variance was explained 39.12% and KMO was 0.724 (chi-square = 14026.471, df = 1153, sig. = 0.00). Consequently, the CMV and missing data are not threatened with the dataset of the study. After conducting searches on scientific databases, it is possible to conclude that there is a lack of sufficient prior studies linking challenges of trainees and organization to internship satisfaction, and as such, exploratory factor analysis (EFA) was the suitable data analysis technique for this study.

Research finding and discussion

Test of exploratory factor analysis (EFA)

The Cronbach’ Alpha is valued with a 95% confidence interval. The overall CA of variables was accepted from 0.666 (Physical requirements/Health) to 0.951 (Student Career Perception) without the presence of PR3 (PR 3_Move around by personal vehicles), PR4 (PR 4_Travel in tour vehicles (minibus, bus) -> for car-sick students), and WH1 (WH 1_Must be on time always) due to theirs corrected item-total correlation <0.3 (details in Table 3) (Hair et al., 2006). The findings suggested hospitality and tourism students best prepare themselves for internship term like full-timers (Chen & Shen, 2012) with personal vehicles for flexibility, maintaining good physical conditions to work long hours on the bus especially on tour packages, and punctuality has been seen as a matter of course in any workplace, i.e., Hongkong trainees (Robinson et al., 2015) (Lam & Ching, 2007).

Table 3. Cronbach’s Alpha results.

Variables	Cronbach’s Alpha	Cronbach’s Alpha Based on Standardized Items	N of Items	Notes
SC	.891	.894	12
CC	.874	.875	7
PR	.666	.676	4	Exclude PR3, PR4 < 0.3
PSS	.906	.906	10
DFS	.908	.908	8
WH	.821	.823	5	Exclude WH1 < 0.3
WE	.884	.885	6
IS	.900	.900	7
CP	.951	.952	15
AS	.876	.879	4
ES	.871	.874	6

Source: authors’ own contribution.

The overall KMO of all dependent variables (i.e., self-confidence, communication and conduct, physical requirements, problem-solving skills, supervision, working hours, and working environments) was 0.793. The KMO ratio of all independent variables (i.e., internship satisfaction, career perception, academic support, and enterprise support) was at 0.866 with Sig of Chi-Square for both factors was 0.000 (p < .005). The results of the rotated component matrix showed that 11 observed variables (7 independent variables and 4 dependent variables) had a loading factor greater than 50%. The tests proved that all exploratory factors analysis were appropriate to be conducted (see detail in Table 4).

Table 4. KMO and Bartlett’s Test results.

KMO and Bartlett’s Test
	Independent variables	Dependent variables
KMO	0.793	0.865
Approx. Chi-Square	15038.858	10593.029
df	1326	496
Sig.	0.000	0.000
Loading Cumulative %	71.437	75.054

Source: authors’ own contribution.

After exploring the model, a nonparametric bootstrapping process is applied to evaluate the structural model and test the significance of path models. In this process, 5000 random samples are calculated, with replacement from the original sample, and the indirect effects of interest are gauged from each bootstrap sample. This result in a sampling distribution could be employed to build a confidence interval (Preacher et al., 2007). To access whether the relationships (weak/strong) among median variables the Pearson Correlation coefficient was calculated. The Pearson Sig. (2-tailed) correlation among IS, CP, ES, and AS dependent variables with SC, CC, PSS, DFS, and WE independent variables were less than 0.05. Thus, there were linear relationships among those variables. The correlation between PSS, WH, and IS was strongest with the coefficient of r = 0.77 and between PR and IS the correlation was the weakest (r = 0.000).

The independent variables introduced into the regression run affected 79% of the variance of the dependent variable and the remaining 21% was due to exogenous variables and random errors at adjusted R2 value of 0.77. There was the value of Durbin coefficient – Watson in the range of 1.5 to 2.5. The ANOVA resulted statistically significant p-value i.e., p = .000 (p < .05) and F = 34.196. Therefore, the multiple linear regression models are suitable for data sets and can be used. According to Sig testing of the regression coefficient of the SC, CC, PSS, DFS, WH, and WE independent variables, the results were significant but PR variable. So, the SC, CC, PSS, DFS, WH, and WE independent variable was the explanation for the IS dependent variables, PR variable was excluded from the model. There are multi-linearity occurrences because the VIF coefficients of the independent variables were higher than 2. It is therefore imperative for students of hotel and tourism management to notice the hardest challenge of problem-solving skills and working hours to enhance internship satisfaction such a low-cost approach to attract internship students (Hussien & Lopa, 2018). However, physical requirements were not the hard thing to overcome for interns which has no significant impact on student internship satisfaction for both increasing the student career perception and the supports of educationers and employers (Chen & Shen, 2012).

Hypothesis testing

The 9 over 10 hypotheses were accepted by data (see Table 5). The variables of internship satisfaction were supported by Self-confidence (SC), Communication & Conduct (CC), Problem-solving skills (PSS), Difficulties in supervision (DFS), Working hours (WH), Working environments (WE), Internship Satisfaction (IS), Student career perception (CP), Academic support (AS), and Enterprise support (ES).

Table 5. Hypothesis testing.

Hypothesis	Path	Adjusted R Square	Coefficient	F	Durbin-Watson	Sig.	Decision
H1	SC–>IS	.17	.138	7.752	1.882	.006	Supported
H2	CC–>IS	.22	.156	9.921	1.854	.002	Supported
H3	PR–>IS	.000	.051	1.045	1.865	.307	Not supported
H4	PSS–>IS	.77	.281	34.196	1.825	.000	Supported
H5	DFS–>IS	.17	.140	7.956	1.846	.005	Supported
H6	WH–>IS	.77	.282	34.326	1.942	.000	Supported
H7	WE–>IS	.56	.242	24.796	1.845	.000	Supported
H8	IS–>CP	.53	.235	23.348	1.904	.000	Supported
H9	IS–>AS	.04	.083	2.732	2.123	.099	Supported
H10	IS–>ES	.29	.178	13.038	2.094	.000	Supported

Source: authors’ own contribution.

So, the output has its standardized regression:

• IS = 0.138*SC + 0.156*CC + 0.281*PSS + 0.140*DFS + 0.282*WH + 0.242*WE

• Internship Satisfaction = 0.138*Self-Confidence + 0.156*Communication & Conduct + 0.281*Problem Solving Skills + 0.140*Supervision + 0.282*Working Hours + 0.242*Working Environments

In sum, the hypothesized model exhibits a good fit with the data collected. The highest value to others effecting student internship satisfaction was working hours (R² = 0.77 and β = 0.282 to 0.281, p < .000). This output is in lined with study of Richardson (2008) mentioning the special working condition in the hotel and tourism industry such as late working shift, working in broken shift and on holidays. Besides, it is lower wages or even no pay for interns as study of Teng (2008), some responses in this research request to have proper payments as “Pay the salary according to the effort that students spend.” Besides, the problem-solving skills factor (R² = 0.77 and β = 0.281, p < .000) is as the most important variable for leading the internship satisfaction like study of Hussien and Lopa (2018). The expected problem-solving skills for interns are as listening, keeping calm, presenting the incident, empathy, identifying and handling the problem, etc.

The lowest value to others effecting student internship satisfaction was self-confidence and supervision factor (R² = 0.17 and β = 0.138 to 0.140, p < .006). This study’ results gather different point of view with research of Lam and Ching (2007). The authors used quantitative approach to confirm the essential role of supervision on student internship satisfaction. However, the output suggested the least important role of the difficulties coming from supervision and individual self-confidence (i.e., Be prepared with new environment, new task, new skills, etc.) through the internship terms. The data is less likely concern on the post and during internship activities and supports. Whereas, some responses from this study mentions as

“On the post-internship career, I want teachers to share more stories during the internship,” “Students should prepare their own physiology before the internship,”

“All students must be proactive.”

On the other side, some trainees expect to have superior’ attention as

“More interaction between businesses and students,” and wish to get the advanced knowledge for career path to “Create conditions to orient the future.”

Additionally, the working environment accounts in internship efficient as

“No matter what position or rank an employee is, the business side needs to listen to the shared opinions and contributions from employees, including interns to be able to create an environment where school work has fun and more effective,” till finishing the intern terms as “Businesses listen to suggestions from the end of the internship”

The association between internship satisfaction and student career perception was significant (R2 = 0.53 and β = 0.235, p < .000). In other words, enhancing internship satisfaction was the value added of the degree of student career perception. Using mixed-methods to investigate the motivators of internship satisfaction, then examine its impact on career perception takes better contribution on the scientific research compared to studies using either quantitative or qualitative approach of Lu and Yirik (2014), Lam and Ching (2007), the study’s outputs confirm the correlation of student internship satisfaction and career choices, especially the capability to clearly define the job requirements, extend relationship, increase business communication skills, and enhance the self-development for further.

The significance of educator support (R2 = 0.04 and β = 0.083, p < .099) and employer support (R2 = 0.29 and β = 0.178, p < .000) is unable to deny their roles in the student success of work placement. Firstly, this study’s results suggest familiar points of views with studies of Stansbie and Nash (2016), Zopiatis and Theocharous (2013). There are some possible ways for schools to increase student self-confidence, communication skills, etc. through workshops, alumni activities, feedback survey before, during and the end of the internship program. In addition, some opinions from this study needs to keep in mind as

“The school needs to regulate with hotels working hours for students. Because of the characteristics of the hotel and restaurant industry, students must often participate in many activities at jobs. Every day I came home after working 8 hours, very tired. A 5-day working week doesn’t seem to be enough time for making school report. Not to mention rather often businesses ask students to work overtime when being lack of manpower, student can refuse once or twice, but cannot refuse all the times. I expect the school to reconsider this issue,”

“Suggestions on the part of the school: it is necessary to select and learn the business environment more carefully before offering posts to students. In my case, the attitude of interviewers of some enterprises was unprofessional. They changed interview appointment many times, then refused to accept internship finally, which makes student waste time and lose the opportunity to get an internship at other businesses.”

To employers, they should assign work in accordance with intern’s health, and with mentors if possible. In the other expectation, interns hope to be facilitated integration of corporate culture and received greater opportunities for self-development, i.e.

“Allocate reasonable time for students to practice while completing the graduation report in the best way”

Consequently, the overall suggestion from our respondents is like

“The school should hold a friendly talk with or organize workshop for students before the internship, not only from alumni but also from lecturers who have a lot of experience to enhance students’ confidence and help them with communication skills necessary for working environment.” Other common issues should be also shared such as: “Senior employees sometimes take advantage by giving the work burden to interns, assigning inappropriately, causing pressures at work; people may use unconstructive words, trainees having no voice (no opportunities to contribute ideas and feedback to businesses about personal encounters); How should students behave in this case?” Others say: “I think students should be receptive to the practical sharing, prepare mentally well to get the best internship, save time to learn career skills. Business does not have to take the time to resolve the individual problems mentioned above. In addition, students need to have mind-set to dedicate benefits to the business, before claiming too many benefits for themselves. On the business and school side, I suggest the school should link up with more businesses and will “send” students interns in a group format or according to a pre-internship survey on students’ expectation of business and work – instead of students having to submit their own application CV. Although submitting CV by oneself is also a way for students to express themselves, but in my opinion, the fact that an individual integrates into the business environment is not easy for everyone to do, so the rate of pressure is very high, leading to incomplete internship results, or even losing interest in chosen career. Therefore, the school can practically support students. That is to use the reputation of the school to send, create opportunities for students to have a good foundation and develop themselves in the best way in the business”.

Conclusion

Theoretically, this research suggests a model for student intership satisfaction with challenges that students need to overcome and can overcome with good preparation in Vietnam context. Practically, the results and opinions collected from students through the scaling open many topics that schools can prepare for students through workshops with participation of businesses, alumni and lecturers. Besides, the results suggest other researches on expectations from the businesses and how much language plays its part in bringing confidence in communication for students. Our paper is important practical implications in the qualification assurance of the education (educator) and training (employer) program.

Educating and maintaining potential qualified employees in the workplace is becoming one of the crucial factors for the sustainable development strategy of institutions and organizations (Lam & Ching, 2007; Richardson, 2008). To carry out this objective successfully, educators and organizations should not only improve practical and thorough courses for training but also need to continuously support students with the challenges they have to face in working environment and build in the skills and psychology to prepare themselves better for a satisfactory career internship. According to the results, this study suggests three practices for internship satisfaction in the H&T industry. Firstly, it is necessary for students themselves to update and self-trained before the internship. Not only should students prepare physically and psychologically they should also be aware of working conditions, activities, and initiatives to enhance soft skills (i.e., self-confidence, communication and conduct, and problem-solving skills). Physical requirement of the career is a must, students should recognize early to train themselves.

Secondly, educators and organizations should prepare longer and better for internship training program also. Students in Vietnam still have difficulties in effective communication and problem solving. These skills can be provided through workshops and activities at schools. Besides enterprises should be more willing in helping their potential coworkers/subordinates to adapt to the policies and regulations at the workplace (i.e., supervision, working hours, and working environments). From the above result, trainers/employers need to give a proper preparation in term of survey, workshops, internship allocation, receiving feedbacks and sharings to internship students – future employees – to create more chances for them to apply the trained knowledge and skills from school.

Thirdly, according to the results of EFA effect of internship satisfaction, although understanding the motives and difficulties of interns in both trainees and trainers (including academy and enterprise) side is important, highlighting student career perception in H&T leads to a stronger desire of employees to stay long with the profession. Thus, our finding suggests that a simultaneous application of both individual and organization concern is better than one of these alone. For example, in addition to the fact that institutions should prepare the proper knowledge and skills of training program for the internship satisfaction to students as potential employees, people/management should have an innovative policy to support new employees in H&T industry and others.

Limitations and further studies

Although this study likely fulfills the research gaps mentioned in the introduction section, this study also contains limitations which will be rooms for further researches.

Firstly, following Lam and Ching (2007), a leading role in organizing internship programs is institutions to involve students and employers to participate in the planning stage to consolidate a training program for students. This argument has not been discovered by previous studies in this context. Thus, further study is suggested to explore the additional effects of institutions on internship satisfaction.

Secondly, Zopiatis and Theocharous (2013) propose an internship model from pre-internship, actual internship, post-internship, and future intention to pursue a hospitality career upon graduation that highlights the supervisor’ role for a success intern as an independent variable influencing training practices (Zopiatis and Theocharous, 2013). This means that policies to develop internship satisfaction may play the roles of indirect and direct effects on student intentions; on this, there is a lack of published articles. Therefore, it is important to carry out a study that will explore the indirect influence of supervision assistance on internship satisfaction, such as longer intention in H&T industry or better support of enterprise.

In addition, limitations also included the limited sampling frame with only four H&T schools participated in this research. Therefore, the outputs could not be generalized to other samples in other context properly. Future studies should involve a bigger number of sample size and H&T institutions to minimize potential bias in the account of expectation and satisfaction.

Additional information

Funding

This work was supported by the Hoa Sen University [No.1538/QD-DHHS-QL.NCKH&HTQT].