Answer Happy

11. I.B. Normal, a graduate student at Skew U., conducted a study with four groups. The first three groups are treatment groups, and the fourth group is a control group. The following data are obtained: Treatment 1 9 8 7 10 5 9 Treatment 2 7 8 7 4 5 Treatment 3 Control 5 7 6747 452FSN 7 7 a. Normal's adviser says that the first question Normal should address is whether the mean of the treatment subjects differs from the mean of the control subjects. The adviser tells her to perform a t test comparing the 18 treatment subjects to the 6 control subjects. In other words, the adviser rec- ommends that the three treatment groups be combined into one group, ignoring (for this analysis) the distinction among the three treatment groups. What did Normal find? (Hint: It will be helpful for Parts c and d that follow if you analyze these data as a one-way ANOVA, using the principles discussed in Chapter 3.) b. Normal was rather disappointed with the result she obtained in Part a. Being the obsessive type, she decided also to test a contrast whose coefficients were 1, 1, 1, and -3. What did she find?