# Answers to Test Yourself

Below are answers to the chapter Test Yourself feature.

**(1) **d **(2) **b **(3) **c **(4) **d **(5) **c** (6) **a **(7) **b **(8) **b **(9) The Cognition class**, where you scored one standard deviation above the mean (z=1). In the Research Methods class, you scored less than one standard deviation above the mean (z=0.8). **(10) **z=1**(11) **A z-score is a number that compares the original score to the mean of the distribution. It allows for better comparisons of scores from two (or more) different scales.**(12) **a.) 5% b.) 98% c.) 79% d.) 47% **(13) **85 **(14) **6.7** (15) **d **(16) **c **(17) **b **(18) **a **(19) **e** (20)** a **(21)** a **(22)** a **(23) **In hypothesis testing, we are relying on a probability—not a certainty—to make a decision. Therefore, errors are possible. **(24) **The alternative hypothesis is: Staying up all night decreased your final exam scores. The null hypothesis is: Staying up all night increased your final exam scores or made no difference. This is a one-tailed test. **(25)** We can reject the null hypothesis that staying up increases or has no effect on your final exam scores. A z-score of -1.79 shows a probability of 4% (0.037) in the tail of the distribution of sample means, which falls below our alpha level. The results suggest staying up all night decreased your final exam scores. **(26) **Correct decision **(27)** Increase the sample size. Enlarging the sample size could result in obtaining a significant difference between groups that is based on subject differences unrelated to the study.