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Distribution Analyses |
The default adds a least squares regression line.
You can also specify your own reference line
by choosing Method:Specification and specifying
both the intercept and slope.
If you select a Weight variable, you can add
a weighted least squares regression line to the normal QQ plot.
If the data are normally distributed with mean and
standard deviation
and if each observation has approximately
the same weight (w0),
then the least squares regression line has
approximately intercept
and slope
for vardef=WDF/WEIGHT
and slope
for vardef=DF/N.
A normal QQ plot with a least squares reference line is shown in Figure 38.36. Use the sliders to change the intercept and slope of the reference line.
Figure 38.36: Normal QQ Plot with a Reference Line
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