\u02c6 Y X 8 10B 245 The standard deviation of points about the regression line

ˆ y x 8 10b 245 the standard deviation of points

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ˆ Y = X + 8 10B. 2.45 The standard deviation of points about the regression line (standard error) is 2.45. 11. Yes
89 Answers: Chapter 15 1. Categorical or frequency data 2. See p. 428 of your text 3. See pp. 230-431 of your text 4. k stands for k-k-categories (number of groups) 5. A 6. See text 7. D 8. B 9. H 0 : The incidence of depression is independent of season. H 1 : The incidence of depression is not independent of season. χ 2 crit = 11.35 χ 2 = 22.77 Reject H 0 The incidence of depression is independent of season (they are related). 10. H 0 : observed frequencies are equal to the expected frequencies H 1 : observed frequencies are not equal to the expected frequencies χ 2 crit = 7.82 χ 2 = 27.2 Reject H 0 Local viewers prefer some evening news programs over others. 11. H 0 : Book-carrying styles are independent of gender H 1 : Book-carrying styles are not independent of gender χ 2 crit = 5.99 χ 2 = 51.2 Reject H 0 Men compared with women tend to carry books down at their side rather than in front of them. 12. Chi-square test of independence: consider 2 variables at once to determine if they are independent (related). Chi-square goodness of fit test: consider 1 variable at a time. Compares actual data to what we expect by chance.
90 Final Exam: Sample Test Answers 1) A 2) A 3) C 4) B 5) A 6) C 7) D 8) D 9) A 10) D 11) D 12) B 13) C 14) D 15) B 16) C 17) D 18) B 19) B 20) C 21) STEP 1: H 0 : ρ = 0 H 1 : ρ 0 Null: The correlation does not exist in the population Alternative: The correlation does exist in the population STEP 2: df = n - 2 = 28 - 2 = 26 r crit = ±0.374 STEP 4: Reject the null ....... so, yes there is a relationship What proportion of the variability .... ? .5476 22) STEP 2: df = (3-1)(2-1) = 2 χ 2 crit = 5.99 STEP 3: χ 2 obtained = 1.02 + 3.93 + 1.44 + 5.53 + .16 + .63 = 12.71 STEP 4: Reject null conclusion? Gender and smoking status are not independent. There is a relationship between gender and smoking status 23a) r = +0.5658 = +.57 23b) Y = .0453X + 7.41 23c) .0453 23d) 10.898 rounds to 10.90 23e) a. weight; time 24) critical = 5.99; χ 2 obtained = 6.67; Reject 25) median 6 mode 7 26) Adding a constant to each score will change the mean without having an effect on the standard deviation. Add 308 to each score. 27) c. mode 28a) 29.7% z = +0.09 z = -0.71 area = .0359 area = .2611 .0359 + .2611 = .2970 28b). 489 29)STEP 1: H0: μ 1 = μ 2 H 1 : μ 1 μ 2 STEP 2: df = 18 t crit = ±2.101 STEP 3: t obtain = -1.5 STEP 4: Fail to reject null 30a) C 30b) A 30c) A

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