Table 2.

Retention models Dependent variable: R_t=1 if participant returned to the study visit, R_t=0 otherwise

	Model 1		Model 2
	Coeff.	AME	Coeff.	AME
Medium Incentive for staying free of STIs (M)	0.319 (0.216)	0.078 (0.052)	0.938** (0.394)	0.132** (0.054)
High Incentive for staying free of STIs (H)	0.380* (0.221)	0.093* (0.053)	0.841* (0.433)	0.120** (0.059)
Medium Incentive for study visits only (Mv)	0.467** (0.219)	0.113** (0.052)	0.719* (0.433)	0.104* (0.061)
Covariates for: distance to clinic (quintiles)	N		Y
personal characteristics	N		Y
lagged outcomes	N		Y
Pseudo R-squared	0.006		0.283
Observations	681		397
p-value (test: M = H)	0.79		0.81
p-value (test: M = Mv)	0.51		0.61
p-value (test: H = Mv)	0.71		0.79

Notes:

^*p<0.10;

^**p<0.05;

^***p<0.01.

Table presents coefficients from logit models and average marginal effects (AME). The dependent variable is the vector R which contains R₁, R₂ and R₃. We defined R₁ as a retention dummy equal to 1 if the participant returned to the first follow-up (at month 6); and equal to 0 if he did not. R₂, and R₃ were defined analogously for the second follow-up (at month 12), and third follow-up (at month 18).

Reference category was the control group. Covariates: Quintiles of distance to the clinic (in kilometers); personal characteristics (age, schooling, marital status, age of first sex, previous STI and HIV tests, as well as housing characteristics); and lagged outcomes (of number of sexual partners, condom use and incident sexually transmitted infections).