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Probability Charts

Probability charts display the cumulative distribution relative to a uniform (linear) or normal distribution function. The probability chart can plot the cumulative distribution for one or more numeric variables.

Normal Probability Graphs

In a normal probability chart, if the normal distribution adequately describes the data, the plotted points fall approximately along a straight line.

A Normal Probability Chart

A Normal Distribution Histogram

Uniform Probability Graphs

In a uniform probability chart, if the uniform distribution adequately describes the data, the plotted points fall approximately along a straight line.

A Uniform Probability Chart

A Uniform Distribution Histogram

Normal Probability Plots and Accompanying Shapiro-Wilk Test

  • Normal probability plot that is provided as an option for testing normality, allows adding Shapiro-Wilk normality test to the plot output (see below an example of probability plots and the corresponding Shapiro-Wilk test results for two independent sample samples).
  • The significance level (α) is set to 0.1 by default. You can edit the α value.