7.14 Learning Activity
In these activities you will use the file Census.sav. The overall goal is to run the Independent-Samples T Test, to interpret the output and visualize the results with an error bar chart.
The file Census.sav, a PASW Statistics data file from a survey done on the general adult population. Questions were included about various attitudes and demographic characteristics.
1. We want to see whether men and women differ in their mean socioeconomic index (sei) and their age when their first child was born (agekdbrn). First, use the Explore procedure to view the distributions of these two variables by gender. Are they similar or different? Do you see any problems with doing a t test?
2. Now do a t test for each variable, by gender. Is the homogeneity of variance assumption met, or not? What do you conclude about mean differences by gender?
3. Create an error bar chart for each variable by gender. Is the graph consistent with the result from the t test?
4. Now do the same analysis with the variable race, testing whether there are differences in sei and agekdbrn comparing whites to blacks. Although race has three categories, you can use only two categories in the t test. As before, first use the Explore procedure to view the distributions of these two variables by race? Are they similar or different? Do you see any problems with doing a t test?
5. Now do a t test for each variable, by white versus black. Is the homogeneity of variance assumption met, or not? What do you conclude about mean differences between whites and blacks?
6. Create an error bar chart for each variable by race. Is the graph consistent with the result from the t test?
7. For those with more timed: How could you display an error bar chart with only the categories of white and black, not other? There are at least two methods.
