Question

In: Statistics and Probability

7 and 8 go together 7.  Two groups of subjects participated in an experiment designed to test...

7 and 8 go together

7.  Two groups of subjects participated in an experiment designed to test the effect of frustration on aggression.  The experimental group of 40 subjects received a frustrating puzzle to solve, while the control group of 70 subjects received a very easy version of the same puzzle.  Levels of aggression was measured for both groups where higher scores are indicative of higher levels of aggression.  The experimental group (high frustration) had a mean aggression score of 4.0 and a standard deviation of 2.0.  The control group (no frustration) had a mean aggression score of 3.0 and a standard deviation of 1.5.  Using these results, formulate a research and null hypothesis and test the null hypothesis at the .01 level of significance.

8.  Assume you collected larger samples of individuals to test your null hypothesis in question #7.  Specifically, the sample sizes increased to 200 subjects in each group.  Do your results and conclusions change from the test of the smaller sample sizes?  (You must show your work).

Solutions

Expert Solution

7)We have to test

Here is the mean of the experimental group and is the mean of the control group.

The level of significance is . The sample sizes are . The degrees of freedom is

Here, the sample means are . The sample standard deviations are .

The test statistic is

The P-value of the test is

Since , we reject the null hypothesis.

We conclude that the aggression levels of the experimental group is higher than that of the control group at 99% confidence.

8)When the sample sizes are ,

The test statistic is

The P-value of the test is

Since , we reject the null hypothesis.

We conclude that the aggression levels of the experimental group is higher than that of the control group at 99% confidence.

The conclusion does not change.


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