# Question

Using the data in Table 13.2, ask whether people’s first guess is usually better than their second guess. (This parallels advice that you often receive about test taking to the effect that you should not go back and change a guessed answer unless you are sure that your new answer is correct. Vul and Pashler found a significant difference, but they had many more participants.)

## Answer to relevant Questions

Assume that the mean and the standard deviation of the difference scores in Exercise 13.6 would remain the same if we added more subjects. How many subjects would we need to obtain a t that is significant at a 5 .01 ...What would happen if we took the data from the anorexia example in Table 13.1 and reexpressed the dependent variable in kilograms instead of pounds? Create a scatterplot of the data in Exercise 13.6, and compute the correlation between the two sets of scores. What does this say that is relevant to the answer to Exercise 13.7? Using the data in Appendix D, compare grade point averages for those having ADDSC scores of 65 or less with those having ADDSC scores of 66 or more. What is the role of random assignment in the anorexia study?Post your question

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