# Chapter 12 homework

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Emma Sibley 6,10,12,14,18,20,28 skip c 6. A related sample because related samples t test is more useful. 10. a. Interpreting your results b.Reporting e ff ect sizes is considered good practice when presenting empirical research findings in many fields. The reporting of e ff ect sizes facilitates the interpretation of the substantive, as opposed to the statistical, significance of a research result. 12. a. We use paired t test because it tests the same subject twice b. We use two independent groups t test to do it. c. We use two independent groups t test to do it. 14. a. b.
c. d.There is su cient evidence against the null hypothesis. Thus, it can be said that the time feels longer when people are bored compared to when they are not bored. e. f.Using the two approaches, we can see that boredom is important in determining how quickly time seems to pass. As per the confidence interval, the minimum time di ff erence for the given sample is approximately 4 minutes, while the maximum time di ff erence is approximately 7 minutes. 18. a. b.
c. P-value = 0.495 d. The relationship is not statistically significant 20. The test here is the independent samples t-test. Hence, the null hypothesis and alternative hypothesis are, Null hypothesis: There is no significant di ff erence between the two means from the two populations. Alternative hypothesis: There is a significant di ff erence between the two means from the two populations. From the critical values of the t table, we get 40 degrees of freedom and a 0.05 level of significance; the critical value of t is 2.0211. Since the obtained value of t is +4.55, which is greater than the critical value of t, which is 2.0211, the null hypothesis is rejected. Hence, the alternative hypothesis may be accepted. Thus, we may conclude that the di ff erence between the two populations is significant. 28. a. Increasing the sample size, increasing the significance level, reducing the measurement error b. Maximizing the power minimizes the type II error of the procedure. This means that the probability of accepting the null hypothesis when the alternative hypothesis is true is reduced to the minimum. This would mean an increase in the type II error. So, the power is generally maximized by keeping the type I error at a fixed level.