comparison of efficacy between a new drug taken by some patients and a standard drug taken by other patients. Methods of estimation for SMCV and c+-probability in matched contrast analysis may differ from those used in unmatched contrast analysis. Unmatched samples Consider an independent sample of size , from the group . 's are independent. Let , and When the groups have unequal variance, the maximal likelihood estimate (MLE) and method-of-moment estimate (MM) of SMCV () are, respectively and When the groups have equal variance, under normality assumption, the uniformly minimal variance unbiased estimate (UMVUE) of SMCV () is where . The confidence interval of SMCV can be made using the following non-central t-distribution: where Matched samples In matched contrast analysis, assume that there are independent samples from groups ('s), where . Then the observed value of a contrast is . Let and be the sample mean and sample variance of the contrast variable , respectively. Under normality assumptions, the UMVUE estimate of SMCV is where A confidence interval for SMCV can be made using the following non-central t-distribution: See also Dual-flashlight plot References Effect size Analysis of variance