The effects of survey modality on adolescents' responses to alcohol use items.
BACKGROUND
We examined differences in response to self-reported alcohol use items by survey mode, whether self-report differences were the result of modality effects or self-selection, and whether these differences varied across the treatment and control arms of a preventative intervention trial.


METHODS
Data from an existing alcohol prevention trial were used to estimate the effect of survey modality on adolescent's self-reported alcohol use at ages 17 to 18. Estimates were derived from regression models controlling for self-reported alcohol use during 8th grade, measured using a single survey modality, as well as time invariant selection factors.


RESULTS
No statistically significant survey modality effects were found. No differential effects of survey modality were observed by assigned intervention group.


CONCLUSIONS
We provide initial evidence that adolescent alcohol prevention trials may use multiple survey modalities when necessary to increase response rates without harming interpretation of intervention effects.