Re: Continuity correction.


"a.riva@UCL" <anto.ilmago@xxxxxxxxx> wrote in message
news:1193155810.098400.152250@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 23 Oct, 17:03, Ken Butler <but...@xxxxxxxxxxxxxxxx> wrote:
On Tue, 23 Oct 2007 15:44:31 -0000, "a.riva@UCL"

<anto.ilm...@xxxxxxxxx> wrote:
So, this means that if I want to calculate the probability associated
to X>=n (with X positive this corresponds to the right tail of the
distribution) I should convert everything to the calculation of
P(Z>=n-0.5) so that I include n. And using NORMSDIST(Abs(z)), the
cumulative probability left to n-0.5 is NORMSDIST(Abs(z(n-0.5))), and
the probability associated with the right tail is 1-
NORMSDIST(Abs(z(n-0.5))). Is this right?

I don't claim to be an expert in NORMSDIST, but it looks right to me.
--
Ken Butler, Lecturer (Statistics)
University of Toronto at Scarborough
butler (at) utsc.utoronto.cahttp://www.utsc.utoronto.ca/~butler

Great!!!

Thanks a lot!!! Unfortunately Excel is really limited for statistical
analyses, but it's generally the software that we use to create all
our databases, and sometimes it's really quicker to try to implement
it instead of moving all the data in other softwares...

Cheers,

Antonio.

++++++++++++++++++++++++++++++++++++++++
Actually for Excel 2003 and 2007, NORMSDIST is accurate from z values
of -37.5 upward. The lower limit is from the lower limit of the IEEE-754
double. There is a region of around z from -3 to -8 where the accuracy drops
to 6 significant decimal digits. Outside of this the accuracy is in the
region of 14 decimal digits.

NORMSDIST has been pretty well tested. See my URL on this (search for "Excel
Faults")

What is your rational for saying that Excel is limited here?

David Heiser


.

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