The mean number of close friends for the population of people living in the U.S. is 5.7. The standard deviation of scores in this population is 1.3. An investigator predicts that the mean number of close friends for introverts will be significantly different from the mean of the population. The mean number of close friends for a sample of 26 introverts is 6.5. Do these data support the investigator’s prediction? Use an alpha level of .01. 

null hypothesis?

one tailed or two tailed?

alternative hypothesis?

what statistic should be used to test the null hypothesis?

calculate the test statistic. what is the outcome/value calculated?

decision based on the results of the statistical test?