After you have read through the Lesson 8 Lab, and you have worked through the Lesson 8 Lab sample data set, you can open up the Lesson 8 Lab Assignment data. This is a set of data from 100 people who completed a scale designed to measure optimism. The first item (column 1) is "Treatment" and refers to 50 people who were given no training in how to be optimistic (a control group labeled with a zero) and 50 people who went through an optimism training program (labeled with a one). The next 7 columns each represent the 7 questions from the optimism scale.

The items are:

1. In uncertain times, I usually expect the best
2. It's easy for me to relax
3. I'm always optimistic about my future
4. I enjoy my friends a lot
5. My life doesn't suck too much
6. I don't get upset too easily
7. Overall, I expect more good things to happen to me than bad

The participants rated each question on a -3 (definitely not) to a +3 (definitely) scale. The researcher believes that their "optimism program" helps people become more optimistic. The null hypothesis is thus that no difference exists between the treatment and control groups.

For this assignment I want you to answer the following questions:

1. Are any of the seven optimism-scale questions "bad"? Tell me which one, and tell me how you know it's bad. (Hint: there is 1 bad question). 4 points
2. Run a split-half correlation on the remaining 6 items. What is the correlation? Does this indicate that the scale is acceptable? 4 points
3. Run a t-test to see if there is a difference between the control group and the treatment group. What is the t-value, and should you "reject the null hypothesis"? 2 points

A couple more hints...

After reading the items you should see that you don't need to reverse code anything.The data is already "clean" so you don't have to run through all of the checking mentioned at the beginning of the Lesson 8 Lab Commentary.

You may type your answers into the bottom of the spreadsheet, or in a Word Document, but whichever you do, be sure to include the Excel spreadsheet with your work so I can take a look at what you did.