Sunday, November 14, 2010
The symbol for a population standard deviation is the Greek letter σ (‘sigma’).
For a sample standard deviation the symbol is s.
The notation for a standard error is given on the right of this post.
We don’t change the symbol on the left. Just switch the sigma in the numerator on the right side to s if you happen to know that it is from a sample (for example you just calculated it from data that is a sample)