Example of Normality Test

A scientist for a company that manufactures processed food wants to assess the percentage of fat in the company's bottled sauce. The advertised percentage is 15%. The scientist measures the percentage of fat in 20 random samples.

The scientist wants to verify the assumption of normality before performing a hypothesis test.

  1. Open the sample data, FatContent.MTW.
  2. Open the Normality Test dialog box.
    • Mac: Statistics > Summary Statistics > Normality Test
    • PC: STATISTICS > Normality Test
  3. In Variable, enter Percent Fat.
  4. Click OK.

Interpret the results

The data points are relatively close to the fitted normal distribution line. The p-value is greater than the significance level of 0.05. Therefore, the scientist fails to reject the null hypothesis that the data follow a normal distribution.

Summary Statistics
N
Mean
StDev
Minimum
Maximum
Anderson-Darling Test
AD-Value
P-Value
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