How can I do standard deviation in Ruby?

Question

I have several records with a given attribute, and I want to find the standard deviation.

How do I do that?

Answer 1

In case people are using postgres ... it provides aggregate functions for stddev_pop and stddev_samp - postgresql aggregate functions

stddev (equiv of stddev_samp) available since at least postgres 7.1, since 8.2 both samp and pop are provided.