How to Sum Squared Deviations with DEVSQ

DEVSQ adds up squared distances from the mean — the “sum of squares” behind variance, ANOVA and regression.

You will learn to

• Calculate the total sum of squares
• Turn a sum of squares into a variance
• Measure how much variation a grouping explains

How it works

DEVSQ(range) subtracts the mean from each value, squares the result and adds them up. This “total sum of squares” (SS) is the raw material of statistics: divide it by n − 1 and you have the sample variance; split it into between-group and within-group parts and you have an ANOVA.

A practical use: compare the within-group sum of squares with the total. 1 − (within SS ÷ total SS) is eta squared — the share of the variation explained by the grouping, such as which fertilizer a plot received.

=DEVSQ(C2:C11)