Data Matters with SPSS®

Activity 9.1

Statistical software can find lines that describe, or fit to points, that line up on a scatter plot. Statistical software can also find lines that fit to points that do not line up, but for this project your task is to get comfortable finding lines to describe points that can be on lines. In fact, you will be looking at only pairs of points and finding the lines that go through both points of each pair.

For the exercise, find the equations of lines and plot those lines for each school district in the following table. Your x-axis variable is Lunch Rate, and your y-axis variable is Reading Pass Rate.

In Variable View of the data editor, label one variable lunch and another pass. Switch to Data View and enter the data for the first district.

Select Analyze, Regression, Linear. Select your y-axis variable (pass), and click on the black triangle next to the Dependent box. Repeat those steps to put your x-axis variable (lunch) into the Independent(s) box. Click OK.

Scroll down to the bottom of the output. For your equation, you need the B’s. They are in a column on the left. The (Constant) B is the y-intercept, and the B for the x-axis variable is the slope.

For example, the table may look like this.

If that were the case, your equation would be Pass Rate = .67075 -.425 X the Lunch Rate .

To get the equations for the rest of the districts, edit the data to enter their values and repeat the same steps.