Data Analysis with Microsoft Excel: Updated for Office 2007

136 Fundamentals of Statistics

Figure 4-4

Frequency

table with

equally

spaced bins

This frequency table gives us a little clearer picture of the distribution of

housing prices back in 1993. Note that almost 80% of the prices are clus-

tered within the fi rst seven bins of the table (representing homes costing

about $129,000 or less). Moreover, there are relatively few homes in the

$160,000–$200,000 price range (only about 4% of the sample). There is,

however, a small group of homes priced above $205,000.

Defi ning Your Own Bin Values

The bin values shown in Figure 4-4 were generated by dividing the range of

prices into 15 equally spaced intervals. This resulted in cutoff values like

64,733 and 75,467. However, in an analysis of pricing we are usually more

interested in even cutoff values like 60,000 and 70,000. The StatPlus Fre-

quency Table dialog box allows you to specify your own bin values in place

of automatically generated ones. Try this now, by creating a frequency table

of housing prices in $10,000 increments, starting at $50,000. You will fi rst

have to enter the bin values into cells in the workbook.

To create your own bin values:

1 Click cell G1, type Price, and press Enter.

2 In cell G2 type 50,000 and press Enter. Type 60,000 in cell G3 and

press Enter.