A researcher uses a repeated-measures study to compare two treatment conditions with a set of 20 scores in each treatment.What would be the value of df for the repeated-measures t statistic?
A)df = 18
B)df = 19
C)df = 38
D)df = 39

Question

A researcher uses a repeated-measures study to compare two treatment conditions with a set of 20 scores in each treatment.What would be the value of df for the repeated-measures t statistic?​
A)​df = 18
B)​df = 19
C)​df = 38
D)​df = 39

Quizplus · Accepted Answer

In a repeated-measures study, the degrees of freedom (df) for the t statistic is calculated based on the number of subjects rather than the total number of scores. Since each subject contributes one pair of scores (one for each treatment condition), the df is calculated as the number of pairs minus one. With 20 pairs of scores (one pair per subject), df = 20 - 1 = 19.

A Researcher Uses a Repeated-Measures Study to Compare Two Treatment