Normality Test

Overview | How to | Example

 

 

Overview

This tool generates a normal probability plot and conducts a hypothesis test to determine is the data is normally distributed. The chart is similar to data plotted onto a normal probability paper with a fitted cumulative distribution function (with parameters estimated based on the data).

Null Hypothesis, H0

Alternate Hypothesis, H1

Data follow a normal distribution

Data do not follow a normal distribution

 

 

How to

At the Excel Menu (For Excel 2007, go to Add-ins first)

  1. Choose ProcessMA > Statistics > Normality Test

  2. In Variable, select the column containing the data (Numeric)

  3. Click OK

 

 

Example

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 data worksheet by choosing ProcessMA > Tools > Data

  2. Choose ProcessMA > Statistics > Normality Test

  3. In Variable, select K - Thickness

  4. Click OK

 

Results & 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.

 

 

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