A discrete choice experiment investigating HIV testing preferences in South Africa

Figures & data

Table 1. Attributes and attribute levels for the HIV test DCE¹⁵.

Attributes	Attribute levels
Testing days	1. Testing is available on weekdays.
	2. Testing is available on weekends.
Distance	1. You will test at your home.
	2. You will test 1 km from your home.
	3. You will test 5 km from your home.
	4. You will test 20 km from your home.
Method for obtaining the sample	1. The sample is taken from the arm.
	2. The sample is taken from the mouth.
	3. The sample is taken from the finger.
Services if HIV positive	1. If you have HIV, you will receive medications at the testing site.
	2. If you have HIV, you will receive a referral to a treatment center for medications.
Confidentiality	1. Without telling; no one will know that you tested.
	2. Your partner will know that you tested.
	3. Without telling; many people who know you will know that you tested.

Figure 1. Example of a choice set¹⁵.

Table 2. Socio-demographic and HIV characteristics of participants.

Socio-demographics	n (%)	HIV-related questions	n (%)
Total participants	199 (100%)	HIV status
		Self-reported negative	187 (94%)
Age		Self-reported positive	12 (6%)
18–34	122 (61%)
35 and above	77 (39%)
		Sexual partners in a lifetime
Gender		None	3 (2%)
Male	33 (17%)	One	72 (36%)
Female	166 (83%)	More than one	122 (61%)
		Missing	2 (1%)
Marital status		Sex for money
Single	86 (43%)	No	195 (98%)
Married or partnership	94 (47%)	Yes	4 (2%)
Widowed/ divorced/separated	19 (10%)
		Other sexually transmitted disease
Education		No	191 (96%)
Elementary	44 (22%)	Yes	8 (4%)
Secondary (Matric)	102 (51%)
Higher education (diploma and above)	53 (27%)	Number of times tested
		1–2 times	39 (20%)
Employment		More than 2 times
Student	19 (10%)	5 or more times	156 (78%)
Unemployed	55 (18%)	Missing	4 (2%)
Employed/self-employed	125 (63%)
		Last HIV test
		Less than 1 year	134 (67%)
Alcohol consumption		1 year and above	63 (32%)
No	86 (43%)	Missing	2 (1%)
Yes	113 (57%)
		Traveled/slept away from home
		No	120 (60%)
		Yes	79 (40%)

Table 3. Random parameter logit model results.

Attribute/level	Coefficient	Estimated standard deviation	Relative importance (%)
Constant (non-random parameter)	0.06 (−0.09 to 0.20)
Time of the week
Weekends	−0.11 (−0.29 to 0.07)	0.60***	4
Weekdays	Reference
Distance
Home	−0.03 (−0.29 to 0.22)	0.72***	10
1 km	Reference level
5 km	−0.17 (−0.49 to 0.15)	0.01
20 km	−0.29 (−0.73 to 0.15)	0.74**
Sample collection
Arm	Reference level
Finger	0.45*** (0.22 to 0.68)	0.55***	15
Mouth	0.18 (−0.05 to 0.40)	0.57***
Collection of medication
Testing site	Reference level
HIV treatment center	−0.18** (−0.33 to −0.02)	0.25	6
Confidentiality
No-one	Reference level
Partner	1.19*** (0.86 to1.51)	1.40***	65
Many people	−0.70*** (−1.08 to −0.33)	1.99***

*** Significant at 0.01; ** Significant at 0.05.

Log-likelihood = −1,235.88.

Pseudo R-Squared = 0.17.

Replications for simulated probs. = 1,000 Halton draws.

Random parameters assumed to be normally distributed.

Fixed number of groups = 9.

Number of observations = 1,791, skipped eight observations.

Table 4. Age sub-group analysis.

Attribute/level	18–34 years old			35 years old and above			Significant difference between both groups
	Coefficient	Estimated standard deviation	Relative importance (%)	Coefficient	Estimated standard deviation	Relative importance (%)	p-value
Constant	0.04 (−0.16 to 0.25)			0.04 (−0.16 to 0.25)
Time of the week
Weekends	Reference level			Reference level
Weekdays	0.12 (−0.15 to 0.38)	0.84***	3	0.12 (−0.96 to 0.35)	0.26	6	0.98
Distance
1 km	Reference level			Reference level
Home	−0.06 (−0.41 to 0.29)	0.71**	18	−0.09 (−0.43 to 0.26)	0.61**	17	0.39
5 km	−0.59** (−1.05 to −0.12)	0.05		0.26 (−0.11 to 0.62)	0.06		0.01***
20 km	−0.78** (−1.414 to −0.12)	1.01**		0.12 (−0.34 to 0.58)	0.08		0.07*
Sample collection
Arm	Reference level			Reference level
Finger	0.57***(0.22 to 0.92)	0.71***	13	0.38**(0.07 to 0.69)	0.29	19	1.00
Mouth	0.33**(0.00 to 0.65)	0.78***		0.01 (−0.29 to 0.32)	0.33		0.55
Collection of medication
Testing site	Reference level			Reference level
HIV treatment center	0.13 (−0.35 to 0.09)	0.25	3	−0.20* (−0.41 to 0.02)	0.18	10	0.47
Confidentiality
No-one	Reference level			Reference level
Partner	1.48*** (0.96− to 1.99)	1.55***	62	0.82*** (0.42 to 1.22)	1.12***	48	0.05**
Many people	−1.15*** (−1.67 to −0.62)	2.08***		−0.16 (−0.65 to 0.32)	1,69***		0.00***

*** Significant at 0.01; ** Significant at 0.05; * Significant at 0.1.

Pseudo R-squared = 0.17.

Log-likelihood = −1,235.88; Fixed number of groups = 9; Number of observations = 1,791, skipped 8 observations.

Replications for simulated probs. = 1,000 Halton draws; Random parameters assumed to be normally distributed.

Table

Socio-Demographics	Age groups		Total
	18-34	35 and above
Age	122 (61%)	77 (39%)	199 (100%)
Gender
Male	18 (15%)	15 (19%)	33 (17%)
Female	104 (85%)	19 (80%)	166 (83%)
Marital Status
Single	75 (61%)	11 (14%)	86 (43%)
Married or Partnership	44 (36%)	50 (65%)	94 (47%)
Widowed	1 (1%)	8 (10%)	9 (5%)
Divorced	2 (2%)	6 (8%)	8 (4%)
Separated	0	2 (3%)	2 (1%)
Education
Elementary	23 (19%)	21 (27%)	44 (22%)
Secondary (Matric)	16 (56%)	34 (44%)	102 (51%)
Higher education   (Diploma and above)	31 (25%)	22 (28%)	53 (27%)
Employment
Student	16 (13%)	3 (4%)	19 (10%)
Unemployed	19 (16%)	11 (14%)	30(15%)
Self-employed	16 (13%)	8 (10%)	24 (12%)
Employed	55 (45%)	46 (60%)	101 (51%)
Housewife/Houseman	16 (13%)	9 (12%)	25 (13%)
Alcohol consumption
Never	35 (29%)	78 (47%)	86 (43%)
Few times per year	43 (35%)	14 (18%)	57 (29%)
Few times per month	38 (31%)	9 (12%)	47 (24%)
Few times a week/daily	6 (5%)	3 (4%)	9 (5%)

Table

HIV Related Questions	Age groups		Total
	18-34	35 and above
HIV Status
No	115 (94%)	72 (94%)	187 (94%)
Yes	7 (6%)	5 (6%)	12 (6%)
Sexual partners in lifetime
None	3 (2%)	0	3 (2%)
One	40 (33%)	32 (42%)	72 (37%)
Two to five	65 (54%)	36 (47%)	101 (51%)
six or more	13 (11%)	8 (11%)	21 (11%)
Sex for money
No	118 (97%)	77 (100%)	195 (98%)
Yes	4 (3%)	0	4 (2%)
Other Sexually Transmitted Disease
No	116 (95%)	75 (97%)	191 (96%)
Yes	6 (5%)	2 (3%)	8 (4%)
Number of times tested
1-2 times	17 (14%)	22 (29%)	39 (20%)
3-4 times	31 (26%)	16 (21%)	47 (24%)
5 or more times	71 (60%)	38 (50%)	109 (56%)
Last HIV test
Less than 1 year	90 (74%)	44 (59%)	134 (68%)
1-2 Years	29 (24%)	21 (28%)	50 (25%)
More than 2 years	3 (2%)	10 (13%)	13 (7%)
Travelled/slept away from home
No	67 (55%)	53 (68%)	120 (60%)
Yes	55 (45%)	24 (31%)	79 (40%)

Ostermann J, Njau B, Brown DS, et al. Heterogeneous HIV testing preferences in an urban setting in Tanzania: results from a discrete choice experiment. PLoS One. 2014;9(3):e92100.

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