An educational psychologist is interested in knowing whether the experience of attending preschool is related to subsequent sociability. She identifies two groups of first graders: those who had...

9. An educational psychologist is interested in knowing whether the experience of attending preschool is related to subsequent sociability. She identifies two groups of first graders: those who had attended preschool and those who had not. Then each child is assigned a sociability score on the basis of observations made in the classroom and on the playground. The following sociability results are obtained: Attended preschoolDid not attend preschool n1 = 12, ?X1 = 204, SS1 = 192n2 = 16, ?X2 = 248, SS2 = 154 a. Set up the appropriate statistical hypotheses. b. Perform the test (æ = .05) 16. The director of Academic Support services wants to test the efficacy of a possible intervention for undergraduate students who are placed on academic probation. She randomly assigns 28 such students to two groups. During the first week of the semester, students in Group 1 receive daily instruction on specific strategies for learning and studying. Group 2 students spend the same time engaged in general discussion about the importance of doing well in college and the support services that are available on campus. At the end of the semester, the director determines the mean GPA for each group: Group 1 (strategy instruction)Group 2 (general discussion) n1 = 14, X1 = 2.83, S1 = .41n2 = 14, X2 = 2.26, S2 = .39 12. Recall the very low correlation between matched pairs in problem 6 (r12 = +.04). Reanalyze these data as if the scores were from two independent groups of eight participants each. a. Compare the two sets of results with respect to sx1 - sx2, the sample of t ratio, and the appropriate statistical decision. 7. Study the following ANOVA summary, and then provide the missing information for the cells designated a-f: SourceSS dfMSFP Between groups(a) 3(b)(c)(d) Within-groups64 (e)(f) _______________________________________ Total349 19 _______________________________________________________________ 9. a. How...