# Re: st: Signtest (statistics question)

 From Roger Newson <[email protected]> To [email protected] Subject Re: st: Signtest (statistics question) Date Mon, 12 May 2003 16:11:30 +0100

```At 15:31 12/05/03 +0100, I wrote:

```
As I understand it, the sign test in Stata works by calculating sign(x1-x2), which is 1 if x1>x2, 2 if x1<x2, and 0 if x1==x2, and then compares the number of positive differences with a binomial with n equal to the number of non-zero differences.
```Sorry, this should have been

```
As I understand it, the sign test in Stata works by calculating sign(x1-x2), which is 1 if x1>x2, -1 if x1<x2, and 0 if x1==x2, and then compares the number of positive differences with a binomial with n equal to the number of non-zero differences.
```Thanks to Nick Cox for pointing out the typo.

Roger

--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
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