We use the GEAR dataset (NIST/SEMATECH e-Handbook of Statistical Methods, http://www.itl.nist.gov/div898/handbook/). We consider that we have 10 machine tools, which produce gears. We have 10 batches of 10 observations. We want to test various assumptions: (1) the average diameter of the gears is the same one for the whole of the machines? (2) The variability of the gear diameter is the same for the whole of the machines?

**Keywords**: analysis of variance, test for equality of variances, bartlett's test, levene's test, brown-forsythe's test

**Components**: One-way ANOVA, Bartlett’s test, Levene’s test, Brown-Forsythe test

**Tutorial**: Anova and Tests for Equality of Variances

**Dataset**: gear_data_from_nist.xls

**Reference**: NIST/SEMATECH, « e-Handbook of Statistical Methods », Chapitre 7 « Product and Process Comparisons ».