Aim To review randomized controlled trials to assess efficacy of a prize-based contingency management procedure in reducing substance use (where a drug-free breath or urine sample provides a chance of winning a prize). Methods A meta-analysis was conducted on articles published from January 2000 to February 2013 to determine the effect size of studies comparing prize-based contingency management to a treatment-as-usual control condition (k=19 studies). Parallel analyses evaluated the efficacy of both short- (k=9 studies) and long-term outcomes (k=6 studies) of prize-based contingency management . Results The average end-of-treatment effect size (Cohen's d) was .46 [95% CI=0.37,0.54). This effect size decreased at the short-term (≤ 3-month) post-intervention follow-up to .33 (95% CI=0.12,0.54) and at the 6-month follow-up time point there was no detectable effect (d=-.09 (95% CI=−0.28,0.10)). Conclusion Adding prize-based contingency management to behavioral support for substance use disorders can increase short-term abstinence but the effect does not appear to persist to 6 months.

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The study of vegetation fluctuations gives valuable information toward effective land use and development. We consider this problem for the East African region based on the Normalized Difference Vegetation Index (NDVI) series from satellite remote sensing data collected between 1982 and 2006 over 8-kilometer grid points. We detect areas with significant increasing or decreasing monotonic vegetation changes using a multiple testing procedure controlling the mixed directional false discovery rate (mdFDR). Specifically, we use a three-stage directional Benjamini-Hochberg (BH) procedure with proven mdFDR control under independence and a suitable adaptive version of it. The performance of these procedures is studied through simulations before applying them to the vegetation data. Our analysis shows increasing vegetation in the Northern hemisphere as well as coastal Tanzania and generally decreasing Southern hemisphere vegetation trends, which are consistent with historical evidence.