DataLab is a compact statistics package aimed at exploratory data analysis. Please visit the DataLab Web site for more information....



Normal Probability Plot

Command: Use the options key in any plot window and select "Norm.Prob.Plt."

DataLab offers the normal probability plot as a graphical technique for assessing whether or not a data set is normally distributed. The observations are plotted against a theoretical normal distribution (the z-scores) resulting in a straight line if the data are normally distributed. The y-axis shows the z-scores of a standard normal distribution in parallel to the corresponding quantiles. Further, the plot also shows the mean and the standard deviation of the selected data, the square of the correlation coefficient, and the ideal line where the data should be located if they are distributed normally.

The normal probability plot can be activated by clicking the options button () in a data plot window. You can select either rows, columns, or the entire data set for the normal probability plot. When selecting row or colums you can select the particular row/column using the eye-dropper button () or the arrow buttons.

Hint: The normal distribution may be tested by using the Kolmogorov-Smirnov-Test, as well (see Statistical Tests).


Last Update: 2012-Jul-25