The exact distribution of the Cohen’s d p in repeated-measure designs

The standardized mean difference, often called the Cohen’s dp, is commonly usedto described difference between means of two measurements. In independent samples,the sampling distribution is known. Herein, we derive the sampling distribution ofthis measure in paired samples, also called repeated measures. The distribution is ageneralized noncentral t distribution which includes the noncentral t distribution asa special case. Applications are discussed.