Pretest and treatment effects in an elementary school-based alcohol misuse prevention program

Area of Science:

• Public Health
• Educational Psychology
• Substance Abuse Prevention

Background:

• School-based programs are crucial for adolescent substance abuse prevention.
• Evaluating intervention effectiveness requires careful consideration of study design and statistical methods.

Purpose of the Study:

• To examine the effects of a pretest and an alcohol misuse intervention in fifth and sixth graders.
• To assess the impact of statistical corrections for clustered data within schools on intervention outcomes.

Main Methods:

• A four-group design (pretest/treatment, pretest/no treatment, no pretest/treatment, no pretest/no treatment) with 5,680 students across 49 schools.
• Statistical analysis including correction for design effects due to school clustering.
• First posttest conducted five months after pretesting and two months after intervention completion.

Main Results:

• Failure to correct for design effects led to overestimation of treatment and pretest significance.
• After correction, a significant treatment effect was observed in students' awareness of the curriculum content.
• No significant treatment effects on alcohol use measures were found at the first posttest, but were expected later.
• Significant pretest effects were noted for peer trouble related to alcohol use and health locus of control.

Conclusions:

• Correcting for design effects is essential for accurate evaluation of school-based prevention programs.
• The intervention successfully increased curriculum awareness, with behavioral changes anticipated over time.
• Pretesting itself may influence student perceptions and behaviors, mimicking intervention effects.