Foa, Rothbaum, Riggs, and Murdock (1991) ran a study comparing different treatments for posttraumatic stress disorder (PTSD). They used three groups (plus a waiting list control)

One group received Stress Inoculation Therapy (SIT), another received a Prolonged Exposure (PE) treatment, and a third received standard Supportive Counseling (SC). All clients were measured at Pretreatment, Posttreatment, and a 3.5 month Follow-up. The data below closely approximate the data that they collected, and the dependent variable is a measure of PTSD.

a. Run a repeated measures analysis of variance on these data.

b. Draw the appropriate conclusions.