Chapter 9 Multiple Regression 385
This plot shows a salary defi ciency that depends very much on the age at
which a female was hired. Those who were hired under the age of 25 have
residuals that average around 0 or a little below. Those who were hired over
the age of 40 are underpaid by more than $5,000 on average. The most un-
derpaid female has a defi cit of nearly $9,000.
Drawing Conclusions
Why should age make a difference in the discrepancies? One possibility is
that women are more likely than men to take time off from their careers to
raise their children. If this is the case, an older male faculty member would
have more job experience and thus be paid more. However, this might not
be true of all women, yet all of the females who were hired over the age of
36 were underpaid.
To summarize, the female faculty are underpaid an average of about
$3,000. However, there is a big difference depending on how old they were
when hired. Those who were hired after the age of 40 have an average defi cit
of more than $5,000. It should be noted that when the case was eventually
settled out of court, each woman received the same compensation, regard-
less of age. You can now close the workbook, saving your changes.
Figure 9-21
Scatter plot
with trend
line added
