## Variance of sample: decreased or not?

One beautiful day I was watching statistics lessons on Khan Academy about variance and standard deviation of sample. To give a quick intro, variance for population is defined by formula , but for sample, it is . You shall not get confused by notation, the only difference is denominator: for sample it is decreased by one. And Sal Khan, the teacher, encouraged me to try and see if it is true. I immediately figured out, that this could be done with not-so difficult program.

Follow me and I’ll show you how I done it!