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Re: st: Output differences, Stata 11 vs Excel 2010
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: Output differences, Stata 11 vs Excel 2010
Date
Fri, 1 Nov 2013 18:30:38 +0000
To take this forward, we need to know _exactly_ what you did in Stata
and in Excel. Ideally, we need to see some sample data, or for you to
do the same thing in Stata and Excel on data that we can all access.
In particular, there are various flavours of t-test, and so the exact
syntax you used is crucial.
Nick
[email protected]
On 1 November 2013 18:26, Yerik Kaslow <[email protected]> wrote:
> I apologize, copy+paste lead to sending before I had finished
> displaying the data. Sorry!
>
> Hi Statalisters,
>
> I've noticed this difference several times before, and it's always
> confused a troubled me a little.
>
> I have clinical trial data I'm analyzing, ttest output is below. The
> means are nearly the same, but the standard deviations are different.
> I've also noticed this also with p-values. The differences are always
> small, but if it's right at the margin of significance, it can
> obviously make a difference.
>
> Does anyone have insight as to why when I run tests of the exact same
> data using Stata, then using Excel, I get slightly different results?
>
> Any insight is appreciated. Thus far I've been taking Stata's output
> over Excel's. I apologize for the bunching together of the output,
> plain text mode is what it is.
>
> Thanks in advance,
>
> Excel Output:
>
> N Int N Con Total N Mean Int Mean Con Diff Int Con SD Int SD Con Pvalue =
> CD1 68 58 126 6.49 6.45 0.04 2.70 2.21 0.9344
> CD2 68 58 126 7.65 7.41 0.23 2.27 2.07 0.5539
> CD3 68 58 126 8.01 7.90 0.12 2.12 2.06 0.7542
> CD4 68 58 126 7.29 7.22 0.07 2.34 2.01 0.8597
> CD5 68 58 126 7.74 6.45 1.29 2.13 2.49 0.2262
> CD6 68 58 126 7.74 7.31 0.42 2.15 2.24 0.2841
>
> Stata Output:
>
> N Int N Con Total N Mean Int Mean Con Diff Int Con SD Int SD Con Pvalue =
> CD1 68 58 126 6.49 6.45 0.04 2.37 1.97 0.9252
> CD2 68 58 126 7.65 7.41 0.23 2.14 1.66 0.5012
> CD3 68 58 126 8.01 7.90 0.12 2.00 1.82 0.7313
> CD4 68 58 126 7.29 7.22 0.07 2.11 1.77 0.8425
> CD5 68 58 126 7.74 6.45 1.29 1.99 2.29 0.1015
> CD6 68 58 126 7.74 7.31 0.42 1.89 1.98 0.2223
>
>
> --
> Yerik Kaslow
> [email protected]
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