How to Calculate Standard Deviation of Records with DSTDEV in Excel

Use DSTDEV to measure how consistent a group of matching records is — like scores given by each exam marker.

You will learn to

• Find the sample SD for one condition
• Find it for two conditions
• Calculate a coefficient of variation with DSTDEV and DAVERAGE

How it works

DSTDEV returns the sample standard deviation of one column for the records that match a criteria range. It treats the matching rows as a sample of a bigger group, which is right when, say, the scripts a marker has graded so far stand for all the scripts they will grade.

A standard deviation on its own is hard to compare between groups with different averages. Dividing DSTDEV by DAVERAGE for the same criteria gives the coefficient of variation — spread as a percentage of the average.

=DSTDEV(A1:D13,"Score",G1:G2)