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Unformatted text preview: Exam 3 Spring 2007 Name_________________________ Psych Stats Spring 2007 Brannick Exam 3 Instructions: Write your name and U number on the scantron. For section, put 1 or 2 if you are in Dan’s lab; put 3 or 4 if you are in Xian’s lab. Answer any 40 of 45 questions on the exam by bubbling in the best of the four alternatives given. For those questions you wish to omit, bubble in “e.” If you answer all 50, I will choose the last 5 for you, so it is in your interest to pick 5 and bubble in “e”. You can take the printed exam with you. Handy formulas: 2 1 2 1 2 2 X X X X S S S + = N s s X X 2 = ; 1 ) ( 2 2 = ∑ N X X s X pairs D pairs D D N S N SD S 2 = = t X X S X X = 1 2 1 2 t X S X = μ D S D t μ = N z z r Y X ∑ = ; X X S X X z = X Y S S r b = ; X b Y a = ; bX a Y + = ˆ ∑ = 2 ) ( G i tot X X SS SS tot =SS b +SS w 2 ) ( A i w X X SS = ∑ 2 ) ( G A g b X X N SS = ∑ MS =SS/df; Df tot = df w +df b; df t = N1; df w = Nk; df b = k1 A W N MS q HSD α = W B obt MS MS F = Critical values of t , alpha = .05, twotails df t df t 1 12.706 6 2.447 2 4.303 7 2.365 3 3.182 8 2.306 4 2.776 9 2.262 5 2.571 10 2.228 1 Exam 3 Spring 2007 Critical values of F Numerator df: df B df W 1 2 3 4 5 5 5% 1% 6.61 16.3 5.79 13.3 5.41 12.1 5.19 11.4 5.05 11.0 10 5% 1% 4.96 10.0 4.10 7.56 3.71 6.55 3.48 5.99 3.33 5.64 12 5% 1% 4.75 9.33 3.89 6.94 3.49 5.95 3.26 5.41 3.11 5.06 14 5% 1% 4.60 8.86 3.74 6.51 3.34 5.56 3.11 5.04 2.96 4.70 2 Exam 3 Spring 2007 Chapter 9 TwoSample t 1.The twosample ttest is used for testing for ________ differences in ________. a. population, means b. population, variances c. sample, means d. sample, variances 2.Suppose we want to know whether Coke or Pepsi tastes better on average to college students. We sample 100 students and assign each randomly so that 50 of them taste Pepsi and the other 50 taste Coke. We ask each to tell us how much they like the taste on a scale from one to ten. What is the independent variable in this study? a. The amount of sugar b. The college students c. The drink (choice of beverage) d. The rating of liking 3.In the study above what is the best way to analyze the data? a. Dependent (related) samples t b. Independent samples t c. Singlesample t d. 2way ANOVA 4.Suppose for the study above, we found the mean of the Coke group is 7 and the mean of the Pepsi group is 8. Further suppose that the variance of ratings within each group is 25. What would our observed value of t be (use the absolute value)?...
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 Spring '10
 Brannick

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