Questions and Answers > Professor Professorson and his colleagues are interested in determining if adolescents who play instructional game apps (such as word puzzles) on their smart phones show increased IQ scores compared to the population mean for IQ

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Professor Professorson and his colleagues are interested in determining if adolescents who play instructional game apps (such as word puzzles) on their smart phones show increased IQ scores compared t... o the population mean for IQ. The team of researchers drew samples of 35 high school students each from the five high schools in the greater Greendale metropolitan area. Following is the data from each high school site: School Population Mean Population SD Sample Mean Sample Size A 100 15 106 35 B 100 15 105 35 C 100 15 99 35 D 100 15 108 35 E 100 15 103 35 Assume a significance level (p) of .05, and assume that this is a one-tailed test (high predicted). Compute a Z test. Remember that you will need to determine the critical value of Z using Table A-1 in the textbook. You will also need to compute standard error (population SD/square root of sample size). And of course you will need to use our Z formula: Z = Sample Mean minus Population Mean divided by Standard Error. Compare the obtained Z test results to the critical value for Z. For which schools were you able to reject the null and find a significant difference in IQ score. Next, find the critical value for Z if we had used a significance level (p) of .01, one-tailed test (high predicted). Compare that critical value for Z against your obtained Z scores. If you had used this as your significance level, how would that have changed your conclusions for each sample? For those samples for which you rejected the null previously, would you have still been able to reject the null? [Show More]

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