RESUMEN
The utility of evaluating mediation effects spans across research domains. The model facilitates investigation of underlying mechanisms of event timing and, as such, has the potential to help strengthen etiological research and inform intervention work that incorporates the evaluation of mediating variables. In order for the analyses to be maximally useful however, it is critical to employ methodology appropriate for the data under investigation. The purpose of this paper is to evaluate a regression-based approach to estimating mediation effects with discrete-time survival outcomes. We empirically evaluate the performance of the discrete-time survival mediation model in a statistical simulation study, and demonstrate that results are functionally equivalent to estimates garnered from a potential-outcomes framework. Simulation results indicate that parameter estimates of mediation in the model were statistically accurate and precise across the range of examined conditions. Type 1 error rates were also tolerable in the conditions studied. Adequate power to detect effects in the model, with binary X and continuous M variables, required effect sizes of the mediation paths to be medium or large. Possible extensions of the model are also considered.
RESUMEN
OBJECTIVE: Internet sex-seeking is common among young men who have sex with men (MSM). However, research examining its association with risky sexual behaviour has produced mixed findings, possibly due to various operational definitions of internet sex-seeking which fail to account for its multi-dimensionality. This study purposed to: (1) examine if the way internet sex-seeking behaviour is operationalised influences its association with risky sexual behaviour (unprotected anal intercourse (UAI) and casual sex) and (2) determine the association of each operational definition with sexual risk. METHODS: We recruited 263 sexually-experienced young MSM (18-29â years) and operationalised internet sex-seeking behaviour in four ways: (i) ever used the internet to meet other men, (ii) currently own a profile on a website dedicated to meeting other men, (iii) ever physically met a man you initially met online and (iv) ever had sex with a man you met online. Using binomial regression, we examined the association of each operationalisation with UAI and casual sex. RESULTS: Only MSM who reported physically meeting a man they met online and those who ever had sex with a man they met online were more likely to report a history of UAI (p<0.05), while MSM who engaged in all forms of internet sex-seeking were more likely to engage in casual sex (p<0.05). However, the strength of these associations varied according to the mode of operationalisation. CONCLUSIONS: The way internet sex-seeking is operationalised in research is differentially associated with sexual risk. Against this backdrop, the utility of these operational definitions in future research and inferences drawn from such research must be interpreted with caution. Findings have important implications for sexual health research and methodology, survey development, sexual health prevention interventions, and evaluating sexual risk among young MSM.
