The welch parameter
What it does
Test variant for the independent t-test and ANOVA: "welch", "student" or "auto"; TRUE or 1 means welch, FALSE or 0 student (as a checkbox, a number or text).
"auto" chooses Student when the groups look alike: Levene p ≥ alphaHomogeneity, variance ratio ≤ varRatioMaxStudent, size ratio ≤ balanceMaxStudent and every group at least smallNForStudent; otherwise Welch. The thresholds are set in Settings.
Thresholds for one formula only: write them instead of the mode, "varRatioMaxStudent=3,smallNForStudent=10" — auto with these thresholds.
Case and spaces around do not matter ("Welch", " student "). An unknown mode or threshold name is an error that lists the variants, for example: welch must be auto, student or welch, got "studnt".
Values
Optional; default "auto".
Allowed values: "welch", "student", "auto", TRUE ("welch"), FALSE ("student")
In plain words
A teacher compared the marks of two classes: 30 pupils in one, 8 in the other, and the marks in the small class were much more spread out. With the setting student, the gap between the averages did not look like luck. With the setting welch, the same marks said it could easily be luck. With groups this unequal, the second answer is the fair one. So the setting can change the answer. If she leaves it on auto, the program looks at her groups, how alike their spread and size are, and picks student or welch for her.
Where you use it
STATS_INDEPENDENT— Independent-samples t-test for two groups: the two selected columns are the groups.STATS_ANOVA— One-way ANOVA: each selected column is a group. Classic (Student) or Welch ANOVA, chosen by welch (auto by default), with homogeneity of variances and post-hoc comparisons.
Examples
"welch""student""auto""varRatioMaxStudent=3"— auto with a looser variance-ratio threshold for this formula
Get it in your sheet
ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)