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FinalReviewProblems06Solutions - 1 Dr Andretti predicts...

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1. Dr. Andretti predicts that racecar drivers will have a greater tendency to make left hand instead of right hand turns. He recruits 32 race car drivers and has them drive down a narrow street, which has just as many possible left hand turns as it has right hand turns. He then records whether the first turn that the drivers take is a left or right hand turn. Help him test his hypothesis by analyzing the data that he obtained with the appropriate statistical test: Raw Data: Turned Left Turned Right 28 4 Solution. ..Run a chi square test to see if there is any preference. Hypotheses: Ho: Racecar drivers exhibit no preference. H1: Racecar drivers exhibit a turning preference. Calculation: Turned Left Turned Right Observed: 28 4 Expected: (16) (16) χ 2 = Σ (O-E) 2 /E = (28-16) 2 /16 + (4-16) 2 /16 = 18.00 df= (C-1)= (2-1) = 1 Decision Rule: χ 2 critical = 3.84 Result: Reject Ho. The racecar drivers had a preference for left hand turns. 2. An anesthesiologist predicts that patients who use PainFree™ will report lower pain scores following surgery than those using PainPax™. Since she has had Psych 60, she knows to randomly assign subjects to the drug conditions. She is also concerned that the type of surgery that the patient had might influence differences in self-reported pain scores between the two groups. Therefore, when assigning a patient to the second drug group, she or he is paired with a patient in the first group who had the same type of surgery. Help her analyze her data by stating the null and alternative hypotheses symbolically and running the appropriate statistical test. Use an alpha of .05. Raw Data: PainPax PainFree 6 2 10 6 4 0 5 7 10 7
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9 5 6 3 9 4 Research Problem: Do patients taking PainFree report lower pain scores than those taking PainPax, given that those patients are originally matched for type of surgery? Statistical Hypothesis: Ho: μ mean difference > 0 H1: μ mean difference < 0 Where mean difference = μ PainFree - μ PainPax If PainFree has a lower mean than the Pain Pax group, then the mean difference under the alternative hypothesis that you would be hoping for would be a mean difference value that is negative, or less than zero. Decision Rule: Reject Ho at .05 level (directional test) if t < -1.89 Raw Data: PainPax PainFree D (Pain Free – Pain Pax) D 2 6 2 -4 16 10 6 -4 16 4 0 -4 16 5 7 2 4 10 7 -3 9 9 5 -4 16 6 3 -3 9 9 4 -5 25 -25 111 Mean D = -3.125 Mean D -3.125 Standard error of mean D 0.766194 Standard deviation of D 2.167124 Calculations: t = mean D / standard error of D = -3.125/.766 = -4.07 Decision: Reject Ho. Interpretation:
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FinalReviewProblems06Solutions - 1 Dr Andretti predicts...

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