Using Frequencies to Study Nominal Data

You manage a team that sells computer hardware to software development companies. At each company, your representatives have a primary contact. You have categorized these contacts by the department of the company in which they work (Development, Computer Services, Finance, Other, Don't Know).

This information is collected in contacts.sav. See the topic Sample Files for more information. Use Frequencies to study the distribution of departments to see if it meshes with your goals.

Running the Analysis

  1. To run a Frequencies analysis, from the menus choose:

    Analyze > Descriptive Statistics > Frequencies...

    Figure 1. Frequencies main dialog box
    Frequencies main dialog box with Department selected as an analysis variable
  2. Select Department as an analysis variable.
  3. Click Charts.
    Figure 2. Frequencies Charts dialog box
    Frequencies Charts dialog box with Pie charts selected as the chart type
  4. Select Pie charts.
  5. Click Continue.
  6. Click OK in the Frequencies dialog box.

Pie chart

Figure 3. Pie chart for department
Pie chart of frequencies for the Department variable

A pie chart is a good visual tool for assessing the relative frequencies of each category. At a glance, you see that the plurality of your contacts work in the computer services departments of their respective companies, followed by those in the financial and development departments.

Frequency table

Figure 4. Frequency table
Frequency table for the Department variable

The frequency table shows the precise frequencies for each category. The Frequency column reports that 30 of your contacts come from the computer services department. This is equivalent to 42.9% of the total number of contacts and 48.4% of the contacts whose departments are known.

Bar chart

A bar chart, ordered by descending frequencies, quickly helps you to find the mode and also to visually compare the relative frequencies.

  1. To obtain an ordered bar chart, recall the Frequencies dialog box.
  2. Click Charts.
    Figure 5. Frequencies Charts dialog box
    Frequencies Charts dialog box with Bar charts selected as the chart type
  3. Select Bar charts.
  4. Click Continue.
  5. Click Format in the Frequencies dialog box.
  6. In the Format dialog, select Descending counts.
  7. Click Continue.
  8. Click OK in the Frequencies dialog box.
Figure 6. Bar chart for department ordered by descending frequencies
Bar chart for department ordered by descending frequencies

Again, you see that the plurality of contacts come from computer services departments.

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