1. Quiz 8 Hypothesis testing Comparing two samples

2. 1. Given two samples of size 35 with normally distributed data and unknown population SDs which statistical distribution should be used to test sample mean differences? a) binomial b) Students t c) standard normal d) chi-squared

3. 2. Which is the correct statistical decision when the test value (TV) falls inside the critical region? a) accept null b) reject null c) not reject H 0 d) not reject H 1 TV

4. 3. What are the critical values for a two-tailed independent-groups t-test assuming equal variances, =0.05 and the two groups have 10 scores each? a) +/–2.262 b) +/–2.228 c) +/–2.101 d) +/–2.093

5. 4. What are the critical values for a two-tailed dependent-groups t-test using =0.05 and a group consisting of 20 subjects? a) +/–2.262 b) +/–2.228 c) +/–2.101 d) +/–2.093

6. 5. Which is the correct statistical decision for a dependent-groups t-test with 10 subjects that yielded a value of 1.96 given =0.05? Use a 2-tailed test. a) reject H 0 ( D =0) b) not reject H 0 c) reject H 1 ( D 0) d) not reject H 1

7. 6. You want to test 2 groups of 35 subjects each. If the data are normally distributed and variances are equal but is unknown which test should you use? a) z-test b) dependent-groups t-test c) independent-groups t-test d) Wilcoxon rank-sum test

8. 7. What is the P-value for a z-test value of 1.40? Assume a two-tailed test is used. a) 0.1616 b) 0.0808 c) 0.0404 d) 0.0500

9. 8. Two sample means from two independent groups were tested with SPSS. The results are shown below. What is the correct statistical decision? a) reject H 0 ( 1 = 2 ) b) not reject H 0 c) reject H 1 ( 1 2 ) d) not reject H 1