AP Statistics: What’s Wrong?
Identify what’s wrong with the following statements that have been used on AP Free Response
Questions.
1. Comparing distributions: The males have a mean score around 36, and the females have a mean
score around 28. The distribution for male scores is more spread out than the distribution for
female scores. The male scores are skewed to the right, but the female scores are symmetric.
Neither distribution has outliers.
2. Choosing the better drug between A and B: Drug A is the better choice. It has a 90% probability
of success and only costs $12 on average to cure the patient.
#3 – 9 are all involving interpreting the results of significance test.
3. Given the high p-value there is sufficient evidence to conclude that using the eyepatch will
indeed increase the response rate.
4. Since the p-value is low, there is not sufficient evidence to reject H0. Thus, we cannot conclude
that the mean IQ score for the class is less than 120.
5. Since the p-value is low, there is not sufficient evidence to reject H0. Thus, we conclude that the
mean IQ score for the class is more than 120.
6. Since the p-value is greater than .05, there is sufficient evidence to accept H0. Thus, we
conclude that the mean IQ score for the class is greater than 120.
7. I reject H0. There is sufficient evidence to conclude that the mean IQ score for the class is less
than 120.
8. Since the p-value is .03, there is only a 3% chance that the H0 is true, so we reject it. There is
sufficient evidence to conclude that the mean IQ score for the class is less than 120.
9. Since the p-value is so small, we reject H0 that the mean IQ score for the class is less than 120.
#10 – 15 are all involving either interpreting a confidence interval or level
10. There is a 95% chance that the mean IQ is between 108 and 124.
11. The mean IQ will be in the interval (108,124) 95% of the time.
12. 95% of the students in the class have an I Q between 108 and 124.
13. I am 95% confident that the interval (108,124) contains the sample mean.
14. 95% of samples taken using the same method would produce a sample mean between 108 and
124.
15. In repeated sampling, 95% of the intervals produced will be centered at the population mean IQ.