Histogram Tool

6.7.8.1. Introduction

Figure 6-33Histogram Tool Dialog

The histogram calculates several kinds of histograms for one or more variables. The types of histogram created are determined by the options selected.

As shown in Figure 6-33, the histogram dialog has four tabs. We will introduce them in sequence.

6.7.8.2. The Input Tab

The Input tab contains the field specifying the data to be used for the histogram.

The Input Range entry contains a single range or a list of ranges, that can be grouped into variables by rows, columns, or areas. The Bin Range entry contains a single range of cutoff values. Both ranges may also include labels.

If the first row or column of the given input ranges, or the first field of each area contains labels, the Input Labels option should be selected.

6.7.8.3. The Bins Tab

Figure 6-34Histogram Tool Dialog Bins Tab

The bins (or classes) for the histogram can either be predetermined by data contained in your workbook or calculated by the histogram tool.

Select the Predetermined Bins option to specify data on your worksheet in the Bin Range: entry. The range should consist of a single column or two columns (the first one containing labels). If the first column of the bin range contains labels, select the Bin Labels option. The values in the last column are used as separators between adjacent bins.

Select the Calculated Bins option to have the bins determined by the tool. Enter the desired number of bins in the N: entry. It is recommended (but optional) that you specify the minimum and maximum cutoffs in the Min: and Max: entries.

6.7.8.4. The Options Tab

The options in the options tab modify the appearance of the histogram:

  • The Pareto option causes the bins to be sorted by decreasing frequency of the first variable.
  • The Percentages option adds a histogram in terms of percentages rather than frequencies.
  • The Cumulative Percentages option adds a cumulative histogram.
  • The Chart option is not implemented.

6.7.8.5. The Output Tab

The Output tab contains the standard output options and fields described at the beginning of Section 6.7 ― Statistical Analysis.

6.7.8.6. A Histogram Example

Figure 6-35Some Example Data
Figure 6-36Specifying Bins
Example 6-8Using the Histogram Tool

For example, you want to calculate a histogram and a cumulative histogram in percentages for a the number of successes in several sequences of trials. The numbers of successes are recorded in column A and the classes of interest in column D with labels in column C (see Figure 6-35).

  1. Enter A1:A21 in the Input Range: entry of the Input tab by typing this directly into the entry or clicking in the entry field and then selecting that range on the sheet. In the latter case the entry will also contain the sheet name.
  2. Since you only have one variable select the Areas or Columns radio button next to Grouped By:.
  3. Select the Input Labels option since the first cell of the Input Range contains a label.
  4. Enter C1:D5 in the Bin Range: entry of the Bins tab. The Predetermined Bins option will now also be selected (see Figure 6-36).
  5. Select the Bin Labels option since the first column of the Bin Range contains labels.
  6. Select the Percentage and Cumulative Percentages options of the Options tab.
  7. In the Output tab, specify the output options as described at the beginning of Section 6.7 ― Statistical Analysis.
  8. Press the OK button.

The results are shown in Figure 6-37.

Figure 6-37Histogram Tool Output