STA 2100 Extra Credit Project - ANOVA STA 2100 Due by May 14, 2017 1. A health psychologist investigates the number of viral infections people contract as a function of the amount of psychological stress they experience during a one-year period. She wants to see if there are significant differences (at the significance level of 0.05) in the mean number of viral infections depending on the amount of stress. She obtained the following data (N=20): _____________________________________________________ Negligible Minimal Moderate Severe Stress Stress Stress Stress _____________________________________________________ 2 4 6 5 1 3 5 7 4 2 7 8 1 3 5 4 2 2 6 8 _____________________________________________________ Please answer the following questions: (a) What are the null and alternative hypotheses? (b) What assumptions should be made? Provide 4 assumptions. 1) 2) 3) 4) (c) What are the critical values? (Specify dfbetween and dfwithin first) (d) Specify the decision rules? (e) Computation: Provide the ANOVA table Source Between Within Total SS df MS F N/A STA 2100 (f) What are your decisions? Provide interpretation of your results. Homework assignment #6 (Due by May 14, 2017) Instruction: Solve the problems #1 by hand and solve #2 using SPSS program. For #2, you should provide means, standard deviations, N, SS, df, MS, F, and p-value, which can be found in the output file. 1. A survey asked college students how they react to their stressful situations during the school year. The most common reactions were drinking, smoking, outing, and doing nothing. Then, the survey asked respondents to choose the one that they are most likely to take when stressed, and to rate the perceived effectiveness of the reaction. Below is a simplified version of the data. Provide the null and alternative hypotheses and test the null hypothesis at the significance level of .05. Based on the results, what conclusion can you draw? Drinking 9 3 6 4 4 Smoking 3 8 7 3 7 3 Outing 2 3 6 8 3 8 Nothing 5 8 1 7 0 6 2. A groups of developmental psychologists wanted to examine under what conditions children of 24 month of age can generate the most number of words. They randomly selected 45 children and randomly assigned them to three different conditions. Then they measured the number of words the children uttered in the three conditions. Specify the null hypothesis and test it at the significance level of .05. What is your conclusion? Make sure to provide the summary table from SPSS. Child playing alone 21 2 6 1 7 53 0 6 10 18 9 23 25 2 24 After bath 47 19 24 12 48 53 20 17 29 41 67 38 51 31 58 After dinner 39 42 10 24 29 34 45 31 35 65 55 57 98 43 75