Automatic ANOVA Analysis (Script Command)

 

See Also:

Scripts

Automatic Statistical Analysis

Automatic Prediction Limit Analysis

 

Processing for the Automatic ANOVA Analysis script command follows this sequence:

 

  1. Transform data to the original concentrations, and replace non-detects with 1/2 of the detection limit.

 

  1. If there are greater than 15% non-detects, a non-parametric test is used. Otherwise, equal variance is tested.

 

  1. Levene's Test for Equal Variance is applied. If the data set does not exhibit equal variance, a non-parametric test is used. Otherwise, normality is tests.

 

  1. If there are greater than 50 measurements, the Shapiro-Francia test for normality is applied. If there are fewer than 50 measurements, the Shapiro-Wilks test for normality is applied. If the normality passes, a parametric ANOVA is applied. If the normality test fails, the data set is log-transformed, and steps 3 and 4 are applied to the natural logarithm of the data.

 

  1. If a parametric test is appropriate, the parametric ANOVA test is applied to the original data or natural logarithm of the data as appropriate. If a non-parametric test is necessary, the Kruskal-Wallis non-parametric ranking test is applied.