Psychological Statistics: Conducting Z-Test 
Conducting a z-Test
Psychological Statistics
Module 2: Assignment 2
Argosy University
Gemini Dickerson
3/12/14
A film was shown to 36 students to see if the attitudes of students toward the mentally ill would change. The results of the class of 36 that watched the film had a score of 70. The results of the class that did not watch the film had a score of 75. The standard deviation is 12. When the alpha is set to 0.05. .05 is a mid-probability. It means we’re using to reduce the likelihood of errors. It means there is a 5% chance that an error may occur. These errors usually will lead to the rejection of the null hypothesis when in reality the hypothesis is correct. The null hypothesis describes the population parameters that the data will represent if the predicted relationship does not exist. Alternative hypothesis describes the population that the sample data represents if the relationship does exist. Because the researcher is predicting that the film will change the attitude of the students toward the mentally ill I would think this is the null hypothesis. I say this because he is predicting that the relationship does exist. The alternative hypothesis would be that there was not a change in the attitudes. This study can either be one tailed or two tailed. One tailed is used when the direction the scores is predicted. Two tailed is when the direction of the scores is not predicted. In this case the study is two-tailed. The researcher predicts a change in attitude, but does not specify which direction positive or otherwise. A two-tailed requires that the z score be higher or lower than the one tailed. Due to the alpha being 0.5 or 5% that would leave the score to be above 1.96 or below -1.96. If my calculations are correct. The critical z of this study is calculated by using the following formula z= x- sample mean/ standard deviation. The standard deviation is 12 and there are 36 students so then we must find the
Psychological Statistics
Module 2: Assignment 2
Argosy University
Gemini Dickerson
3/12/14
A film was shown to 36 students to see if the attitudes of students toward the mentally ill would change. The results of the class of 36 that watched the film had a score of 70. The results of the class that did not watch the film had a score of 75. The standard deviation is 12. When the alpha is set to 0.05. .05 is a mid-probability. It means we’re using to reduce the likelihood of errors. It means there is a 5% chance that an error may occur. These errors usually will lead to the rejection of the null hypothesis when in reality the hypothesis is correct. The null hypothesis describes the population parameters that the data will represent if the predicted relationship does not exist. Alternative hypothesis describes the population that the sample data represents if the relationship does exist. Because the researcher is predicting that the film will change the attitude of the students toward the mentally ill I would think this is the null hypothesis. I say this because he is predicting that the relationship does exist. The alternative hypothesis would be that there was not a change in the attitudes. This study can either be one tailed or two tailed. One tailed is used when the direction the scores is predicted. Two tailed is when the direction of the scores is not predicted. In this case the study is two-tailed. The researcher predicts a change in attitude, but does not specify which direction positive or otherwise. A two-tailed requires that the z score be higher or lower than the one tailed. Due to the alpha being 0.5 or 5% that would leave the score to be above 1.96 or below -1.96. If my calculations are correct. The critical z of this study is calculated by using the following formula z= x- sample mean/ standard deviation. The standard deviation is 12 and there are 36 students so then we must find the