This procedure generates a normal probability plot and conducts a hypothesis test to determine is the data is normally distributed.
1. Choose ProcessMA > Statistics > Normality Test.
2. In Variable, select the column containing the data.
3. Click OK.
Optional
4. In Segment by, select a column containing subgroup codes. Each subgroup will be analysed individually.
Note To select a column of data into a textbox, double-click on any of the column names shown in the list on the left of the dialog box while in the textbox.
Variable: Numeric.
Segment by: Text or Numeric. Must contain equal number of data points as the Variable.
You measured the thickness of 30 new widgets made. You want to find out if the data is normally distributed before performing a hypothesis test.
1. Open worksheet ProcessMA > Tools > Data Files > Stat.xls.
2. Choose ProcessMA > Statistics > Normality Test.
3. In Variable, select A – Thickness.
4. Click OK.
Interpretation
The normal probability plot shows that most data follows the fitted line. The p-value is 0.3602 indicates that there is evidence that the data follow a normal distribution.