In this chapter we have used both Minitab and R to construct normal scores plots. In R
this is done using the function qqnorm, which automatically generates the plot. Before we
show its use, we have three important points to note regarding normal scores plots made
with computer packages. First, dierent packages handle ties in dierent ways. The dierent
approaches result in similar-looking plots, however, so we will not dwell on this point. More
noteworthy is the fact that some packages reverse the axes: they plot the population quantiles
on the vertical axis and the sample quantiles on the horizontal axis. In these cases, the slope
and intercept for such a plot have dierent meanings than for the plots we have described;
however, the key point remains the same: data from a normal population should result in a
plot where the points follow a straight line.
In this chapter we have used both Minitab and R to construct normal scores plots. In Rthis is done using the function qqnorm, which automatically generates the plot. Before weshow its use, we have three important points to note regarding normal scores plots madewith computer packages. First, di erent packages handle ties in di erent ways. The di erentapproaches result in similar-looking plots, however, so we will not dwell on this point. Morenoteworthy is the fact that some packages reverse the axes: they plot the population quantileson the vertical axis and the sample quantiles on the horizontal axis. In these cases, the slopeand intercept for such a plot have di erent meanings than for the plots we have described;however, the key point remains the same: data from a normal population should result in aplot where the points follow a straight line.
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