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. Author manuscript; available in PMC: 2013 Nov 1.
Published in final edited form as: Contemp Clin Trials. 2012 Aug 7;33(6):1105–1116. doi: 10.1016/j.cct.2012.08.002

Figure 1.

Figure 1

shows the power of our study at testing different effect sizes using one-sided two sample t-test at alpha level of .05 when the attrition rate is 20% or 0. The observed effect sizes of Logic Memory from the 7 studies in the literature are marked in the plot. Each number on the plot denotes the sample size of the corresponding study. From this plot, a reasonable estimate of the effect size of logic memory is about .45 and the power is within .56 to .64 depending on the attrition rate. The power of the study is from .64 to .72 if the effect size is .5.