For ChemuT

HW#5 Independent and Paired t-Tests Name______________________________

Part 1: Open Independent t-test HW data set.sav

Rename the variables by placing your last name in front of both of the existing variable names

For example: Class becomes GaddisClass ( My last name is Said)

The Problem:

A high school in the Kansas City School District wanted to assess a new method of testing competency in calculus for its International Baccalaureate students. The district administrators believed that the new method was superior to the old method and that more students would achieve better grades in calculus with the new method. To assess the new test, one of the two classes of calculus was tested using the old method and the other class was tested using the new method. The teachers assigned to this process wanted to see if the new method of testing was indeed better than the old method of testing. Following teaching the same unit of information to their students, each class was given a test to assess competency with the new material. Class A was given the new test and Class B was given the old test. Each class consisted of 20 students. These students had been randomly assigned to their calculus class at the beginning of the school year. Test scores were recorded on a continuous data scale of 0-100 points. Select a test with which you will analyze this data. Assume that the data are normally distributed.

1. State the Null Hypothesis.

2. State the Research Hypothesis

3. What test did you choose to test your hypothesis?

4. What does the information from the Levene’s test, found in the output of this analysis, tell you?

5. What was the calculated t-Test statistic from your test?

6. What was the level of significance obtained by the calculated t-statistic?

7. Have you accepted or rejected the null hypothesis?

8. Calculate the effect size for this analysis. (Show your work)

9. What judgement can you make about this effect size?

10. Write the results of this study as if submitting to a journal. Include the names of the tests for all of the assumptions and their results. Include the name of the main analysis test chosen. Report the means and standard deviations from the two groups, include the degrees of freedom, t-statistic, p value, and effect size in your write up. Include a decision about the null hypothesis. Include a statement about the outcome of the research question.

***This write up should be brief and written in a scientific manner. That means: do not get wordy or verbose.

***All pertinent tables should be included in this homework assignment. PLEASE! Use the copy special option and then paste the tables into your HW using the paste icon for pictures. If the paste icon for pictures does not appear you can do the following:

1. Right click on the table, select copy special, click on Image (JPG,PNG), leave all others checked.

2. Open up PowerPoint and paste the table onto a PowerPoint slide

3. On the slide, put your cursor over the table and right click.

4. Do the same as in Step 1.

5. Now paste the table into your word file. You should now have the paste a picture icon available.

****Do not turn in more than one file/attachment. Everything should be included in your word file.

Part 2: Open Paired t-test HW data set.sav

Rename the variables by placing your last name in front of both of the existing variable names

For example: newtestscores becomes Gaddisnewtestscores ( Use the name Halima)

The Problem:

A high school in the Kansas City School District wanted to assess a new method of testing competency in calculus for its International Baccalaureate students. The district administrators believed that the new method was superior to the old method and that more students would achieve better grades in calculus with the new method. To assess the new test, a class of students taking calculus was tested using the old method and the new method. The teachers assigned to this process wanted to see if the new method of testing was indeed better than the old method of testing. Following teaching a new unit of information to the students, a test to assess competency with the new material was given. The students were randomly assigned to be assessed by either the old test or the new test. Half of the class took the old test and half took the new test. Four hours later, the student were again assessed. This time, those students who took the new test first, now took the old test. Those students who first took the old test, now took the new test. The class consisted of 20 students. Test scores were recorded on a continuous data scale of 0-100 points. Select a test with which you will analyze this data. Assume that the data are normally distributed.

1. State the Null Hypothesis.

2. State the Research Hypothesis

3. What test did you choose to test your hypothesis?

4. You were not asked to assess the data for homogeneity of the variances prior to or during the running of your selected test. What information have you been given that will allow you to estimate for homogeneity of the variances without running a Levene’s test?

5. Was Homogeneity of variances present in the two test groups?

6. What was the calculated t-Test statistic from your test?

7. What was the level of significance obtained by the calculated t-statistic?

8. Have you accepted or rejected the null hypothesis?

9. Calculate the effect size for this analysis. (Show your work)

10. What judgement can you make about this effect size?

11. Write the results of this study as if submitting to a journal. Include the names of the tests for all of the assumptions and their results. Include the name of the main analysis test chosen. Report the means and standard deviations from the two groups, include the degrees of freedom, t-statistic, p value, and effect size in your write up. Include a decision about the null hypothesis. Include a statement about the outcome of the research question.

***This write up should be brief and written in a scientific manner. That means: do not get wordy or verbose.

***All pertinent tables should be included in this homework assignment.

Extra Credit (1pt)

One of the tests shows a degrees of freedom of n-1 and the other, n-2. Why?