# Standard error help answer [closed]

The standard population error of the sampling distribution when we know the population standard deviation is equal to $σ_M = σ/\sqrt n$, or is it, $S_m = σ/\sqrt n$?

• please be more specific what you're trying to ask. Are you trying to distinguish between the standard error of the mean versus the true standard deviation of the sample mean? Apr 6 '13 at 18:46
• As both your formulae are the same, are you just asking whether to use a Greek or non-Greek letter to represent it? Also what do you mean by "population error"? Apr 6 '13 at 21:48
• Oh, I mean the standard error of the sampling distribution when we know the population standard deviation is equal to _________________.
– Luna
Apr 6 '13 at 22:55
• It would not be a sample estimate if $\sigma$ is known. So if by $S_m$ you mean a sample estimate then it is not that. Jun 17 '18 at 21:53

If you know the population standard deviation, the standard error would be $\sigma_M$, since you would base it off the population parameter, $\sigma$. It would be designated $S_M$ or, probably more typically, $S_\bar{X}$, when based off the sample standard deviation.