264 Fundamentals of Statistics
Figure 6-22 indicates that there is a moderate outlier for revenues gener-
ated by rural nursing homes. This outlier may affect the results of our t tests.
One way of dealing with this outlier is to switch to a nonparametric test,
which is less infl uenced by the presence of outlying values.EXCEL TIPS
You can also perform a two-sample t test of your data using the
Analysis ToolPak, supplied by Excel. To perform a two-sample
t test, fi rst load the Analysis ToolPak and then click the Data
Analysis button from the Analysis group on the Data tab.
For a pooled test, click t Test: Two Sample Assuming Equal Vari-
ances and specify the two columns containing the paired data.
For an unpooled test, click t Test: Two Sample Assuming Unequal
Variances.
The Analysis ToolPak does not include confi dence intervals for
the two-sample t.•
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Figure 6-22
Boxplots of
the revenue
data