8. Gravetter/Wallnau/Forzano, Essentials - Chapter 9 - End-ofchapter question 16 People are poor at making judgments about probability. One source of error in judgments of probability is the base rate fallacy in which people ignore the base rates of low probability events. In a study of the base rate fallacy by BarHillel (1980), participants were exposed to a vignette about a traffic accident. In the scenario, a taxicab was observed in a hitandrun accident. In the city where the accident occurred, 85% of cabs are blue and 15% of cabs are green. Later, a witness testified that the cab in the accident was green and the witness was shown to be 80% accurate in identifying blue and green cabs (i.e., 20% of the time, the witness confused the cabs). What do you think is the probability that a green cab was in the hit-and-run? Most participants who encounter this problem report that the probability of the cab being green is much higher than the actual probability of 41%. That is, most participants ignore the fact that green cabs are relatively rare. Suppose that a researcher replicates the BarHillel experiment with a sample of n = 16 participants. The researcher observes an average rated probability of M = 60.06% with SS = 656.66. Use a two-tailed test (a = .05) of the hypothesis that participants showed a base rate fallacy. Assume that u = 41 if there is no base rate fallacy. The null hypothesis is H\": V V V . Complete the following table. 52 SM t Critical Values Significant? V V Y V V t Distribution Degrees of Freedom = 21 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 Compute two different measurements of effect size. (Round your answers to two decimal places) Estimated d = 72