# Essay Psy 315 Week 4

Week 4 Practice Worksheet

Prepare a written response to the following questions.

Chapters 9 &11

1. Two boats, the Prada (Italy) and the Oracle (USA), are competing for a spot in the upcoming America’s Cup race. They race over a part of the course several times. The sample times in minutes for the Prada were: 12.9, 12.5, 11.0, 13.3, 11.2, 11.4, 11.6, 12.3, 14.2, and 11.3. The sample times in minutes for the Oracle were: 14.1, 14.1, 14.2, 17.4, 15.8, 16.7, 16.1, 13.3, 13.4, 13.6, 10.8, and 19.0. For data analysis, the appropriate test is the t-Test: Two-Sample Assuming Unequal Variances.

The next table shows the results of this independent t-test. At the .05 significance level, can we conclude

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Hypothesis Test: Independent Groups (t-test, pooled variance) Larry George 4.77 5.02 mean 1.05 1.23 std. dev. 40 50 n 88 df -0.25000 difference (Larry - George) 1.33102 pooled variance 1.15370 pooled std. dev. 0.24474 standard error of difference 0 hypothesized difference -1.02 t .3098 p-value (two-tailed) -0.73636 confidence interval 95.% lower 0.23636 confidence interval 95.% upper 0.48636 margin of error

Chapters 11 & 12

4. A consumer organization wants to know if there is a difference in the price of a particular toy at three different types of stores. The price of the toy was checked in a sample of five discount toy stores, five variety stores, and five department stores. The results are shown below.

Discount toy Variety Department

$12 15 19

13 17 17

14 14 16

12 18 20

15 17 19

An ANOVA was run and the results are shown below. At the .05 significance level, is there a difference in the mean prices between the three stores? What is the p-value? Explain why an ANOVA was used to analyze this problem.

One factor ANOVA Mean n Std. Dev 13.2 5 1.30 Discount Toys 16.2 5 1.64 Variety 18.2 5 1.64 Department 15.9 15 2.56 Total ANOVA