In the rarer case where the mean of the distribution is *known*, the uncertainty about the standard deviation is given by the formula:

\sigma =\sqrt{\frac{\displaystyle\sum_{i=1}^{n}(x_{i}-\mu)^{2}}{\chi^{2}(n)}} |

[This page provides an explanation of the derivation]

The model Estimate StDev for Normal Distribution When Mean is Known lets you generate values for the above uncertainty distribution for s for a data set.

The formula:

=SQRT(SUMPRODUCT(Data-mu,Data-mu)/Chisquared(n))

is used in the model.

The links to the Estimate StDev for Normal Distribution When Mean is Known software specific models are provided here: