Re: Student's t vs. z tests

[Robert J. MacG. Dawson]

Jon Cryer wrote:
> 
> These examples come the closest I have seen to having a known variance.
> However, often measuring instruments, such as micrometers, quote their
> accuracy as a percentage of the size of the measurement. Thus, if you
> don't know the mean you also don't know the variance.

        You do if you log-transform...

                -Robert Dawson


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