Series: Practical guidance to qualitative research. Part 3: Sampling, data collection and analysis

Figures & data

Table

Sampling	Definition
Purposive sampling	Selection of participants based on the researchers’ judgement about what potential participants will be most informative.
Criterion sampling	Selection of participants who meet pre-determined criteria of importance.
Theoretical sampling	Selection of participants based on the emerging findings to ensure adequate representation of theoretical concepts.
Convenience sampling	Selection of participants who are easily available.
Snowball sampling	Selection of participants through referrals by previously selected participants or persons who have access to potential participants.
Maximum variation sampling	Selection of participants based on a wide range of variation in backgrounds.
Extreme case sampling	Purposeful selection of the most unusual cases.
Typical case sampling	Selection of the most typical or average participants.
Confirming and disconfirming sampling	Confirming and disconfirming cases sampling supports checking or challenging emerging trends or patterns in the data.

Table

	Definition	Aim	Ethno-graphy	Pheno-menology	Grounded theory	Content analysis
Participants of observations	Participation in and observation of people or groups.	To obtain a close and intimate familiarity with a given group of individuals and their practices through intensive involvement with people in their environment, usually over an extended period.	Suitable		Very rare	Sometimes
Face-to-face in-depths Interviews	A conversation where the researcher poses questions and the participants provide answers face-to-face, by telephone or via mail.	To elicit the participant’s experiences, perceptions, thoughts and feelings.	Suitable	Suitable	Suitable	Suitable
Focus group discussion	Interview with a group of participants to answer questions on a specific topic face-to-face or via mail; people who participate interact with each other.	To examine different experiences, perceptions, thoughts and feelings among various participants or parties.	Suitable		Sometimes	Suitable

Table

Face-to-face interviews	Brinkmann S, Kvale S. Interviews. Learning the craft of qualitative research interviewing. 3rd ed. Sage: London; 2014.Rubin HJ, Rubin IS. Qualitative interviewing: The art of hearing data. 2nd ed. Sage: Thousand Oaks (CA); 1995.
Online interviews	Salmons J. Qualitative online interviews. 2nd ed. Sage: London; 2015.
Focus group discussion	Barbour RS, Kitzinger J. Developing focus group research. Politics, theory and practice. 1st ed. Sage: London; 1999.Kruger R, Casey M. Focus groups: A practical guide for applied research. Sage: Thousand Oaks (CA); 2015.

Table

	Ethnography	Phenomenology	Grounded theory	Content analysis
Transcripts mainly from	Observations, face-to-face and focus group discussions, field notes.	Face-to-face in- depth Interviews.	Face-to-face in- depth interviews; rarely observations and sometimes focus group discussions.	Face-to-face and online in-depth interviews and focus group discussions; sometimes observations.
Reading, notes and memos	Reading through transcripts, classifying into overarching themes, adding marginal notes, assigning preliminary codes.	Reading through transcripts, adding marginal notes, defining first codes.	Reading through transcripts, writing memos, assigning preliminary codes.	Reading through transcripts, adding marginal notes, assigning preliminary codes.
Describing	Social setting, actors, events.	Personal experience.	Open codes.	Initial codes.
Ordering	Themes, patterns and regularities.	Major and subordinate statements. Units of meaning.	Axial coding. Selective coding.	Descriptive categories and subcategories.
Interpreting	How the culture works.	Development of the essence.	Storyline about social process.	Main categories, sometimes exploratory.
Findings	Narrative offering detailed description of a culture.	Narrative showing the essence of the lived experience.	Description of a theory, often using a visual model.	Narrative summary of main findings.

Table

Ethnography	• Atkinson P, Coffey A, Delamount S, Lofland J, Lofmand L. Handbook of ethnography. Sage:   Thousand Oaks (CA); 2001.  • Spradley J. The ethnographic interview. Holt Rinehart & Winston: New York (NY); 1979.  • Spradley J. Participant observation. Holt Rinehart & Winston: New York (NY); 1980.
Phenomenology	• Colaizzi PF. Psychological research as the phenomenologist views it. In: Valle R, King M, editors.   Essential phenomenological alternative for psychology. New York (NY): Oxford University   Press; 1978. p. 41-78.  • Smith J.A, Flowers P, Larkin M. Interpretative phenomenological analysis. Theory, method and   research. Sage: London; 2010.
Grounded theory	• Charmaz K. Constructing grounded theory. 2nd ed. Sage: Thousand Oaks (CA); 2014.  • Corbin J, Strauss A. Basics of qualitative research. Techniques and procedures for developing   grounded theory. Sage: Los Angeles (CA); 2008.
Content analysis	• Elo S, Kääriäinen M, Kanste O, Pölkki T, Utriainen K, Kyngäs H. Qualitative Content Analysis: a   focus on trustworthiness. Sage Open 2014: 1–10. DOI: 10.1177/2158244014522633.  • Elo S. Kyngäs A. The qualitative content analysis process. J Adv Nurs. 2008; 62: 107–115.  • Hsieh HF. Shannon SE. Three approaches to qualitative content analysis. Qual Health Res. 2005;   15: 1277–1288.