# How to compute variances from a matrix/table

I have created a matrix/table with an imported dataset. I want to know what the variance is for 3 values at a time but across 68 columns. I would like to do this in an automated way rather than 1 set of values at a time. Is there a way?

I'm new to Mathematica, so if there is a really simple way, I don't know about it yet!

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If your data is stored in data, what does Dimensions[data] say? –  Szabolcs Apr 17 at 3:03
Check the second example in the Basic Examples section of Variance in the docs. –  kguler Apr 17 at 3:07
An example dataset with the desired outcome would be helpful here. –  bobthechemist Apr 17 at 13:49