# If I know the population mean but want to determine the standard deviation for a trail of several events; should I be dividing by the number of events or the number of events minus 1?

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For example, I know the (true) population mean for the sum of 2 six-sided dice is 7.

A series of 6 trials generated the results #{4,11,6,9,12,7}# .

Should I use population variance and standard deviation, or sample variance and standard deviation?

I seem to remember that the reduction of the divisor for a sample was because the sample mean was only an estimate of the true population mean, but hat isn't the case here.

For example, I know the (true) population mean for the sum of 2 six-sided dice is 7.

A series of 6 trials generated the results

Should I use population variance and standard deviation, or sample variance and standard deviation?

I seem to remember that the reduction of the divisor for a sample was because the sample mean was only an estimate of the true population mean, but hat isn't the case here.

##### 1 Answer

Jun 11, 2016

It depends...

#### Explanation:

Are you wanting the standard deviation from your model or the standard deviation in the data?

If wanting the standard deviation from the mean of the model then you would divide by

If wanting the standard deviation of the data then you would divide by