move over to your Measure column. Here is where we tell SPSS how the data were measured. Test yourself here. Is the Year variable nominal, ordinal, or scale? How about the Motor_vehicle_thefts variable? Here’s the screenshot to answer these two questions:
In the lower left corner of the screen, switch to Data View, and here’s what you will see:
Now, enter your data from Table 3.6 into your spreadsheet. When you get done, here’s what you will see:
1 Click on Graphs and then on Chart Builder.
2 Choose Line, and then double-click on Simple Line.
3 Drag the Year variable onto the x-axis and the Motor_vehicle_thefts variable onto the y-axis.
4 Now move over to the Element Properties window. In the Statistic box, click on the dropdown menu, and choose Value. Doing so will allow your y-axis to be labeled correctly.
5 Hit Apply at the bottom of the Element Properties box.
6 Then hit OK in the Chart Builder box, and prepare to be impressed.
Learning Check
1 Use Wendt’s (2013) data and in SPSS, make a bar graph to illustrate sex differences in dysfunctional perfectionism.A:
2 In the previous question, why would it not be appropriate to make a scatterplot to illustrate sex differences in dysfunctional perfectionism?A: A person’s sex is a nominal variable. That is, a person falls into one and only one category on this variable. A scatterplot is appropriate for scale data; bar graphs are appropriate for nominal data.
3 Use Wendt’s (2013) data and in SPSS, make a scatterplot of the relationship between dysfunctional perfectionism and role overload.A:
Notes
1. It certainly does make logical sense to place “first-years” before “seniors” on the x-axis because students have to be first-year college students before they can become college seniors.
2. Of course, there are other pieces of data that the restaurant wanted to know, such as the types of pizzas ordered and whether customers dined in or ordered take-away. However, for the purposes of illustrating time plots, I presented only daily sales of pizzas.
Chapter Application Questions
1 Explain the difference between a bar graph and a histogram.
2 Related to the previous question, why is it that in a bar graph, the bars are not allowed to touch each other?
3 Suppose you are about to get a test back in class. Before the teacher hands back your test, which histogram would you (and other students) prefer to see? Explain your choice.
4 Interpret the information it conveys.
5 In the previous question, why is it an example of a nonlinear relationship?
6 Why can’t we make a bar graph with scale data?
7 Why can’t we make a scatterplot with nominal data?
Answers
1 We use bar graphs to display frequency distributions of nominal data, whereas we use histograms to display frequency distributions of ordinal and scale data.
2 Recall that nominal data are categorical data. That is, a datapoint is in one and only one category. Bar graphs, as we said in the previous question, are meant to represent frequencies for nominal data. Because such data are discrete (i.e., can fall into only one category), they are separate from all other categories. Therefore, the bars do not touch each other.For question 4, consider the following two histograms on the next page that contain the distribution of scores on a class exam.
3 The histogram in Figure 3.18a shows that many students tended to score toward the high end of the distribution on the test, whereas the histogram in Figure 3.18b shows more students toward the low end of the distribution on the test. So before knowing your own score, the top distribution would make you feel better about your chances of scoring well on the test.For question 5, consider the line graph in Figure 3.19.
4 This line graph shows that life satisfaction tends to decline in people’s late teenage years, continuing through their 20s and 30s, but then it starts to increase once people reach their 40s and increases as people continue to age from that point in their lives.
5 This is a nonlinear relationship because the relationship between age and life satisfaction is different across different age levels. That is, it tends to decline in our teenage years until our 40s (a negative linear relationship), but then it tends to increase starting in our 40s as we age from that point (a positive linear relationship).
6 A bar graph displays categories. Scale data do not contain categories, so there is no practical way to make a bar graph with scale data.
7 Nominal data contain categories. But scatterplots are useful only when the two variables being plotted are both scale data. There is no practical way to make a scatterplot with nominal data because categories cannot be plotted on a scatterplot.
Figure 3.18a
Figure 3.18b
Figure 3.19
Questions for Class Discussion
1 A researcher surveyed 10 undergraduate psychology majors about their study behaviors. The following is a list of the number of hours they spent studying on the weekend:What type of frequency distribution graph should be made for these data? Explain your response.
2 Suppose you conducted a survey in which you ask people which wireless provider they use. What type of frequency distribution graph would be most appropriate for your data? Explain your reasoning.
3 Suppose you organized a 5K race. You measured each person’s time to complete the race. What type of frequency distribution graph would be most appropriate for your data? Explain your reasoning.
4 Referring to the previous question, suppose you had asked race participants how many previous 5K races they had participated in. You want to see the relationship between the number of previous 5K races and time to finish the current 5K race. What common visual display of data would be most appropriate for these data? Explain your reasoning.
5 Again
