Essentials

248 APPENDIX BBecause the variances are very similar for the four groups, the pooledvariancest test seems more appropriate. Based on the results above,method makes a significant difference for younger but not older participants.However, this does not imply that the method effect is significantlygreater for the younger group than the older group. A two-wayANOVA is needed to test that difference, as shown in Chapter 7.(b) g (X 1–s pX 2)4.6Younger: Modeling vs. Tutorial: g 4 7 .97 4.6 0.66; between6.926moderate and large3.59Older: Modeling vs. Tutorial: g 6 0 .77 3.59 0.46; moderate7.7967.11Modeling: Younger vs. Older: g 5 2 .27 7.11 0.98; quite large7.2296.10Tutorial: Younger vs. Older: g 5 2 .27 6.10 0.84; large7.229(c) 1– 2 X 1– X 2 t crits X 4.6 1.99 (1.41); so 4.6 2.8 1–X 1Therefore, the 95% CI goes from 1.8 to 7.4.2. (a)Participant No Imagery Imagery D1 8 14 62 11 15 43 7 5 –24 10 16 65 9 9 06 15 16 17 7 8 18 16 20 4ΣD 20; n 8, s D 2.93, D 2 0 2.58