Effects on behavioral intentions for marijuana use and fighting were not statistically significant in either study¶

Claim · All claims
Evidence · 1 study · causal r? · q3

Subclaims¶

q3 i? In the RCT, intentions for marijuana (effect size 0.47) and intentions for fighting (0.13) were not statistically significant. → What Works Clearinghouse 2006 q2 i? In the quasi-experimental study, intentions for marijuana (0.44) and fighting (0.47) were likewise not statistically significant. → What Works Clearinghouse 2006

Evidence¶

What Works Clearinghouse 2006¶

What Works Clearinghouse, U.S. Department of Education. (2006). WWC Intervention Report: Too Good for Drugs and Violence. https://www.mendezfoundation.org

q3 · i? · causal · r?

WWC-calculated results for the RCT's intention outcomes, with effect sizes calibrated using the odds ratio formula; both marijuana and fighting intentions were marked "ns" (not statistically significant). The quasi-experimental study's intention outcomes (0.44 and 0.47) were also ns.

"Intentions for marijuana (no intentions) Grades 9–12 197/16 76 of 85 students 89 of 112 students 2.18 0.4710 ns +18"

Discussion¶

Related Claims¶

• Facing History and Ourselves shows no discernible effects on student behavior, with self-reported fighting differences neither statistically significant nor substantively important — related
• Statistically significant effects reported by the CDP studies were not statistically significant as recalculated by the WWC — related
• In the RCT, the average effect across knowledge, attitudes, and values outcomes was substantively important (0.35) but not statistically significant, with several individual outcomes null — related
• Three of seven knowledge, attitudes, and values outcomes favor Facing History and Ourselves, including relationship maturity (best response) with effect size 0.45, but none remain statistically significant after WWC corrections — related