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 people in general on this questionnaire is 75, with a standard deviation of 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?

1. What does it mean to set alpha at .05?
2.What is your null hypothesis? Alternate hypothesis?
3.Is this a one-tailed or two-tailed hypothesis?
4.What is the critical z?
5.Calculate the obtained z. Do you reject or fail to reject the null hypothesis?
6.State in words what you have found.

1. To set alpha at .05 means that we are willing to accept a 5% chance of making a Type I error - rejecting the null hypothesis when it is actually true. In hypothesis testing, alpha (α) represents the significance level or the probability of rejecting the null hypothesis when it is true.

2. In this scenario, the null hypothesis (H0) would be that watching the film does not change students' attitudes towards the chronically mentally ill. The alternative hypothesis (Ha) would be that watching the film does change the students' attitudes.

3. Based on the research question, the researcher is predicting a change in attitude, without specifying whether it would be an increase or decrease. Since there is no specific direction mentioned, this is a two-tailed hypothesis.

4. The critical z-value is the value obtained from the standard normal distribution table, corresponding to the chosen significance level (α). For a two-tailed test with a significance level of .05, the critical z-value would be ±1.96.

5. To calculate the obtained z-value, we need the sample mean, standard deviation, and sample size. The sample mean given is 70, and the standard deviation for people in general is 12. The sample size is 36. Using these values, we can calculate the obtained z-score using the formula:

z = (sample mean - population mean) / (population standard deviation / sqrt(sample size))

z = (70 - 75) / (12 / sqrt(36))
z = -5 / (12 / 6)
z = -5 / 2
z = -2.5

Since this is a two-tailed test, we compare the obtained z-value (-2.5) with the critical z-value (-1.96 and 1.96). Since -2.5 falls outside the range between -1.96 and 1.96, we reject the null hypothesis.

6. Based on the hypothesis test, we have found evidence to support the claim that showing the film changes students' attitudes towards the chronically mentally ill. The obtained z-value suggests that the students' attitudes were significantly different from the population mean, indicating a change in attitude after watching the film.