6.4 Assessing Normality; Normal Probability Plots
The normal probability plot is a graphical technique to identify substantive departures from normality
I.e., if the sample normal distribution, the 1-12 positions corresponding y value should be the value of this column
Noted：
When required before transition to the statistical normal distribution of the histogram by the normal curve, the abscissa of each class, in this case the sample itself.
By the table3 correspondence, mapping:
According to the above rule determines normal circumstances.
Note: If two or more observations in a sample are equal, you can think of them as slightly different from one another for purposes of obtaining their normal scores.
As shown, may be normal-score value to a corresponding percentage
A probability or percent scale is used instead of normal scores
Detecting Outliers with Normal Probability Plots
a removing outlier obtained b
Thereby determining whether the data is normally distributed