Which is the appropriate method for controlling familywise error in a situation that involves comparing each group in a research study with a single reference group?

A) Dunnett Test
B) Scheffé Test
C) Tukey Test
D) Cohen d

The Dunnett test is appropriate when comparing multiple treatment groups with a single control or reference group, and controls for familywise error by adjusting the significance level of each comparison. The Scheffé and Tukey tests are more appropriate for situations where all pairwise comparisons are being made among multiple groups. Cohen d is a measure of effect size, and not a method for controlling familywise error.