Table 3.

Power to detect a treatment effect size of .4 or .3 as a function of sample size, difference between treatment arms, and standard deviation

Mean and SD of Buspirone Arm for Cohen’s d of .4
Sample Size	Mean=20, SD =15 Diff* = 6 days	Mean=18, SD=10 Diff = 4 days	Mean=16, SD =5 Diff = 2 days
150	77% (19%)	71%	69%
200	86% (12%)	81%	81%
250	92% (7%)	89%	89%
Mean and SD of Buspirone Arm for Cohen’s d of .3
Sample Size	Mean=18.5, SD =15 Diff* = 4.5 days	Mean=17, SD=10 Diff = 3 days	Mean=15.5, SD =5 Diff = 1.5 days
250	74%	68%	67%
300	81%	75%	74%
350	86%	81%	80%

Note:

^*Difference in days is equal to the difference between the mean maximum days of continuous cocaine abstinence in the buspirone and placebo arms. Parenthesized figures indicate percent of cases that failed to converge, when convergence failure rates exceeded 5%.