Answers to Test Yourself
(1a) IV = video condition (view crime discussion video or not), DV = recognition memory score. (1b) This is a two-tailed test (no prediction is made about which group will score better), so for H1: in the population, the video condition affects recognition scores, for H0: in the population, the video condition does not affect recognition scores. (1c) Reject the null hypothesis because p < a--the independent variable (viewing the discussion of the crime with false information or not viewing the discussion) has an effect on memory accuracy. (1d) If the null hypothesis is true and you reject it, you are making a Type I error. (2a) A one-tailed test should be used, because the researcher is predicting that people will be better than chance (>50%) if they have poker abilities, but less than chance does not indicate poker abilities. (2b) H1: in the population, “better than average” poker players will guess the type of card chosen at a rate higher than 50%, H0: in the population, “better than average” poker players will guess the type of card chosen at a rate lower than or equal to 50%. (2c) p > a, so the null hypothesis must be retained. The researcher cannot conclude that the poker players can predict another player’s hand at better than chance accuracy. (2d) This would be a Type II error, because the null hypothesis was retained when in reality it is false. (3) Type I errors occur when a researcher rejects a null hypothesis that is actually true. Type II errors occur when a researcher fails to reject a null hypothesis that is actually false. The probability of a Type I error is set by alpha. (4) A quasi-experiment--two groups are compared, but no independent variable is manipulated. (5) one-tailed; two-tailed. (6) reject. (7) c. (8) outlier. (9) high. (10) null.