> I agree, NORMSDIST is OK. But ZTEST doesn't use it, but calculates all > itself.
It actually does use gauss() - which I assume is at the heart of NORMSDIST. GAUSS()=NORMSDIST+0.5 I think. > Wouldn't it be more natural to calculate a "real" sigma than a variance? > I mean > sigma = sqrt((fSumSqr - fSum*fSum/rValCount)/(rValCount- 1.0)); > in stead of > sigma = (fSumSqr - fSum*fSum/rValCount)/(rValCount-1.0); > and than for both cases use your suggestion > PushDouble(0.5 - gauss((mue-x)*sqrt(rValCount)/sigma)); Whatever :). Yours is certainly clearer, mine a bit faster. > But both ways would have > fSumSqr - fSum*fSum/rValCount > which might give similar problems like in issue 78250. Yes - really should use the same algorithm as VAR, DVAR, STDEV etc. > The real problem I see is, that a function, even corrected in one of > this ways, does not follow the definition in ODF1.2. What to do? I don't think that ODFF (draft of 16May08) has the definitive answer to this: "TODO: OOo Calc and Gnumeric produce the same results. Excel (2007 beta) claims to calculate the one-tailed test. All produce different results than expected! What OOo Calc and Gnumeric calculate is out of my scope. Excel tries to calculate the probability by integrating from minus infinity to z and substracts this from one. That would only be right, if the absolute value of z is taken, not the signed z! (I speak already of the one-tailed results for this case, so no confusion here.) So, either I made a mistake/misinterpretation or all three apps don't get it right(TM)." We've gone back to basics and understand exactly what Excel does, which is admittedly daft, and is not what they say in their knowledge base article (revised Jan08) or Help. We can reproduce the results in R. It all supports what 'TM' says. We can document how to use the function sensibly, even if Excel's documentation is faulty. So as far as I can see we've got the thing nailed... Do you agree? I have a load of things to feed back to ODFF anyway; I'll just add this to the list. Best regards David --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
