True/False (two points each)

Chapter10

1. In an experiment involving matched pairs, a sample of 15 pairs of observations is collected. The degree of freedom for the t statistic is 14. true

2. In testing the difference between two means from two independent populations, the sample sizes do not have to be equal to be able to use the Z statistic. true

3. In testing the difference between the means of two independent populations, if neither population is normally distributed, then the sampling distribution of the difference in means will be approximately normal provided that the sum of the sample sizes obtained from the two populations is at least 30. true

4. If the limits of the confidence interval of the difference between the means of two normally distributed populations were 0.5 and 2.5 at the 95% confidence level, then we can conclude that we are 95% certain that there is no significant difference between the two population means. false 5. When comparing two population means based on independent random samples, the pooled estimate is used if the variances are unknown and assumed equal. true

Chapter 12

6. The chi-square distribution is a continuous probability distribution that is symmetrical. false

7. In a contingency table, when all the expected frequencies equal the observed frequencies the calculated 2 statistic equals 0. true

8. In a contingency table, if all of the expected frequencies equal the observed frequencies, then we can conclude that there is independence between rows and columns. false

9. In performing a chi-square test of independence, as the difference between the respective observed and expected frequencies decrease, the probability of concluding that the row variable is independent of the column