Question

A child psychologist treats four children who are afraid of snakes with a behavioral modification procedure called systematic desensitization. In this procedure, children were slowly introduced to a snake over four treatment sessions. Children rated how fearful they are of the snake before the first session (baseline) and following each treatment session. Higher ratings indicated greater fear. The hypothetical data are listed in the table Sessions Baseline 1 23 4 7 543 6 6 44 6 773 7 (a) Complete the F-table. (Round your value for F to two decimal places.) Source of Variation Between groups Between persons Within groups (error) Total df MS Fobt 23.69 X 7.90 8.30 2.69 0.90 8.56 34.93 0.95 X 15 (b) Compute a Bonferroni procedure and interpret the results. (Assume experimentwise alpha equal to 0.05.) Ratings of fear significantly decreased from baseline to Session 3. Ratings of fear also significantly decreased from baseline to Session 4 Ratings of fear significantly decreased from baseline to Session 4 None of the pairwise comparisons are significant. 0 Ratings of fear significantly decreased from Session 1 to Session 4, Ratings of fear also significantly decreased from Session 2 to Session 4 Ratings of fear significantly decreased from baseline to Session 3. Ratings of fear also significantly decreased from Session 1 to Session 4

Answer 1

applying two way ANOVA:

Source of Variation	SS	df	MS	F
between groups	32.8	4	8.2	9.111
between persons	1.2	3	0.4
Error	10.8	12	0.9
Total	44.8	19

b)

rating of fear signifcantly decreased from baseline to session 4