1. In your own words explain the difference between a chi-square goodness of fit and a chi-square test of independence.

Chi Square Goodness of Fit

1. A professor in the psychology department would like to determine whether there has been a significant change in grading practices over the years. It is known that the overall grade distribution for the department in 1998 had 14% A's, 26% B's, 31% C's, 19% D's, and 10% F's. A sample of n = 200 psychology students from last semester produced the following grade distribution:

A	B	C	D	F	TOTAL
32	61	64	31	12	200

1. Explain why the goodness of fit is the correct test to analyze this data.

1. What are the null and research hypotheses for this test?

Conduct a chi-square goodness of fit analysis at the .05 level of significance.

1. What degrees of freedom and critical value should you use to evaluate the significance of your test statistic?
2. Based on this critical value, should you reject or fail to reject your null hypothesis?
3. Explain your results to a friend you met at the coffee shop without using statistical jargon (e.g., don't say anything about rejecting, hypotheses, alpha levels, etc.).

Chi Square Test of Independence

1. A statistics instructor would like to know whether it is worthwhile to require students to do weekly homework assignments. For one section of the statistics course, homework is assigned, collected, and graded each week. For another section, the same problems are suggested each week, but the students are not required to turn in their homework. At the end of the semester, all students take the same final exam. The grade distributions for the two sections are as follows:

FINAL EXAM GRADE: A B C D

Homework : 12 15 17 5

No Homework : 12 21 28 25

1. Explain why the test of independence is the correct test to analyze this data.

1. State the null and alternative hypothesis for this test.

1. Do these data indicate a significant difference between the grade distributions for students with homework versus students with no homework? Test with a = .05.

1. What degrees of freedom and critical value should you use to evaluate the significance of your test statistic?

1. Explain your results to a friend you met at the coffee shop without using statistical jargon (e.g., don't say anything about rejecting, hypotheses, alpha levels, etc.).