Psychological Statistics
posted by Patience .
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 (alpha), does showing the film change students’ attitudes towards the chronically mentally ill?
What is your null hypothesis? Alternate hypothesis?
Is this a onetailed or twotailed hypothesis?
What is your obtained z?
What is the critical value for z?
Do you reject or fail to reject the null hypothesis?
State in words what you have found.

Null:
Ho: µ = 75
Alternate:
Ha: µ ≠ 75
Test would be twotailed because the alternate hypothesis does not show a specific direction (results could be in either tail of the distribution curve).
Do a ztest using the data listed in the problem.
Check a ztable for the critical values to compare to the test statistic calculated from the ztest. Use .05 level of significance for a twotailed test to find the critical values. Compare the test statistic to the critical values from the table. If the test statistic exceeds the critical value (either tail), reject the null and conclude a change. If the test statistic does not exceed the critical value (either tail), do not reject the null (there is no difference).
I hope this will help get you started. 
Assignment 2: Conducting a zTest
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?
What does it mean to set alpha at .05?
What is your null hypothesis? Alternate hypothesis?
Is this a onetailed or twotailed hypothesis?
What is the critical z?
Calculate the obtained z. Do you reject or fail to reject the null hypothesis?
State in words what you have found. 
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?
What does it mean to set alpha at .05?
What is your null hypothesis? Alternate hypothesis?
Is this a onetailed or twotailed hypothesis?
What is the critical z?
Calculate the obtained z. Do you reject or fail to reject the null hypothesis?
State in words what you have found