A researcher predicts that watching a film on institutionalization will change students' attitudes about chronically mentally ill patients. The researcher randomly selects a class of 36 students, shows them the film, and gives them a questionnaire about their attitudes. The mean score on the questionnaire for these 36 students is 70. The score for a similar class of students who did not see the film is 75. The standard deviation is 12. Using the five steps of hypothesis testing and the 5% significance level (i.e. alpha = .05), does showing the film change students' attitudes towards the chronically mentally ill?

What does it mean to set alpha at .05?

What is your null hypothesis? Alternate hypothesis?

Is this a one-tailed or two-tailed hypothesis and why?

What is the criterion z?

Suppose the obtained z was -2.5. Do you reject or fail to reject the null hypothesis?

State in words what you have found.