1. The Wechsler Adult Intelligence Scale is standardized to have a mean of 100 and a standard deviation of 15. If we draw a random sample of 25 people from the population, what is the probability of obtaining (a) a sample with a mean IQ of 95 of less? (b) a sample with a mean IQ of 105 or greater? (c) Within what central limits would 95% of the sample means fall?

2. The symbolic expression p < .001 occurs in the results section of a research report. Does this indicate that the investigator used the very conservative level of significance to evaluate the outcome of that particular test? Explain.

3. In 1977, studies found that laboratory rates fed huge does of the noncaloric sweetener saccharin developed bladder tumors. The results were highly statistically significant. By itself, is this strong enough evidence to remove saccharin from the market?

4. Explain what is meant by a Type I error, a Type II error, and statistical power. How are they related?

5. Explain the differences between a one-sample t test, an independent samples t test, and a dependent samples t test? In what instances are each used? Relative to one another, how do they compare in terms of statistical power?

6. Explain the difference between statistical significance and practical significance.