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Time-varying effects of predictors of sexual risk behavior in adolescents and young adults. Sara A. Vasilenko, Stephanie T. Lanza, Runze Li & Jennifer S. Barber. Outline. Background on time-varying processes in sexual behavior Time-varying effect model (TVEM) Examples Add Health RDSL - PowerPoint PPT Presentation
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Time-varying effects of predictors of sexual risk
behavior in adolescents and young adults
Sara A. Vasilenko, Stephanie T. Lanza, Runze Li & Jennifer S. Barber
Outline
• Background on time-varying processes in sexual behavior
• Time-varying effect model (TVEM)• Examples
– Add Health– RDSL
• Summary and Implications
Background
• Meaning and riskiness of sexual behavior can vary over time– Adolescence v. Midlife– Time in a relationship
Background
• Traditional methods don’t account for these time-varying processes– Collapse across age, divide into groups– Changes occur in continuous time
TVEM
• Time-varying effect model (Tan et al., 2012; Shiyko et al., 2012)
• Flexible, nonparametric method for analyzing time-varying effects
• Versions for continuous, dichotomous, zero-inflated Poisson outcomes– Logistic TVEM (dichotomous) presented
• Macro available at methodology.psu.edu
Logistic TVEM
• where
TIME-VARYING PREDICTORS OF RISKY SEX OVER DEVELOPMENTAL TIME
Example 1
Sample Questions
• How do odds of having multiple partners change over time from early adolescence to young adulthood?
• How does the association between heavy episodic drinking and multiple partners change over time?
• How do these differ by gender?
Method
• Data from 4 waves of Add Health (ages 12 to 32)
• Participants in 7th to 12th grade during first wave of study, with follow-up interviews 1 year later, 7 years later, and 13 years later
• Contractual data; N=12,051 with 39,063 total person-records
Data Preparation
Measures
• Outcome: Multiple partners in past year
• Predictor– Past year Heavy Episodic Drinking
(Any/None)
Male95% CI Male
Female95% CI Female
Male95% CI Male
Female95% CI Female
TIME-VARYING PREDICTORS OF RISKY SEX OVER TIME IN A RELATIONSHIP
Example 2
Sample Questions
• How do odds of using a condom change over time from the first to 120th week of a relationship?
• How does the association between contraceptive attitudes and condom use change over time?
Method
• Data from the Relationship Dynamics and Social Life (RDSL) Study
• 1,003 women aged 18-20 (35% African American, Mage=18.7)
• Followed weekly for 2.5 years– Up to 130 occasions per person– Used occasions when in a relationship
between 0 and 130 weeks in duration• 29,823 occasions, 608 individuals
Measures
• Outcome: Weekly condom use
• Predictors– Baseline Contraceptive Attitudes (6-item
scale)
Estimate95% CI
Estimate95% CI
Summary
• Rates and predictors of risky sexual behavior can change over time
• TVEM can help uncover processes unfolding in continuous time
• Prevention programs should target predictors relevant to individuals’ ages and stages of a relationship
Acknowledgments
• Grants 2T32DA 017629 and P50-DA010075-17
• Add Health funded by: P01-HD31921 • RDSL funded by: R01 HD 050329 • Thanks to Nicole Butera, John Dziak,
Yasmin Kusunaki, Michael Yang