I can't help but be reminded of learning to ride a bicycle. 99.9999% of
people ride one with two wheels (natch!) - but many children do start to
learn with training wheels......
Alan
dennis roberts wrote:
>
> the fundamental issue here is ... is it reasonably to expect ... that when
> you are making some inference about a population mean ... that you will
> KNOW the variance in the population?
>
> i suspect that the answer is no ... in all but the most convoluted cases
> ... or, to say it another way ... in 99.99% (or more) of the cases where we
> talk about making an inference about the mean in a population ... we have
> no more info about the variance than we do the mean ... ie, X bar is the
> best we can do as an estimate of mu ... and, S^2 is the best we can do as
> an estimate of sigma squared ...
>
> this is why i personally don't like to start with the case where you assume
> that you know sigma ... as a "simplification" ... since it is totally
> unrealistic
>
> start with the realistic case ... even if it takes a bit more "doing" to
> explain it
>
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--
Alan McLean ([EMAIL PROTECTED])
Department of Econometrics and Business Statistics
Monash University, Caulfield Campus, Melbourne
Tel: +61 03 9903 2102 Fax: +61 03 9903 2007
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