# Psychological Statistics

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A researcher predicts that watching a film on institutionalization will change studentsâ€™ 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 studentsâ€™ attitudes towards the chronically mentally ill?

What is your null hypothesis? Alternate hypothesis?
Is this a one-tailed or two-tailed hypothesis?
What is the critical value for z?
Do you reject or fail to reject the null hypothesis?
State in words what you have found.

• Psychological Statistics - ,

Ho: Mean1 = mean2
Ha: Mean1 ≠ mean2

Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√n

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.

This should start you out.

• Psychological Statistics - ,

waht is the null and alternate hypothesis of a researcher prdicts that watching a film institutionalization will change students attitudes about chronically mentally ill patients