Please produce an accurate research design model that dipicts a Pre-test/Post-test study where 200 participants were randomly assigned to one of four treatment groups. Solution There are four treatment groups and 200 participants available Hence divide 200 into 4 equal groups. Give each group of 50, one of the four treatments. Before treatment find the weight and other health particulars about all. After the treatment again find them. Prepare a table for four different groups separately Find mean, variance, std error for each group using df = 50-1 49 The difference is recorded for each group Then for each group difference is calculated for average std deviation..