Hi,
I'm rather new to this, and someone else might like to confirm this - but if you don't know the distribution of a statistic and want to verify its accuracy or compare it with the same statistic of another sample, you can use the bootstrap method. See Efron B. and R. Tibshirani (1993) An Introduction to the Bootstrap, New York, Chapman & Hall. Stata has a bootstrap command and the manual gives quite a good description of it.
Ramani
Roger Newson <[email protected]> wrote:
> At 11:27 29/10/03 +0100, Carmine Ornaghi wrote:
> >hi. I have to compare the mean and the median of a
> >variable for two groups of firms (acquired and
> >acquirer) but this variable is not normally
> >distributed (so that I cannot use ttest).
> >I know the command ksmirnov and median to compare the
> >distribution and the median but they just tell me that
> >they are not equal. When I look at the main statistics
> >(using "summarize, detail" for the two groups), I have
> >that the mean is grater in one group but the median is
> >lower. Any suggestion?
>
> You might use the program -cendif-, part of the -somersd- package, to
> calculate confidence intervals for median differences or ratios. The
> package is distributed with .pdf manuals. In Stata, type -ssc desc
> somersd-
> to find out more.
>
> I hope this helps.
>
> Roger
>
>
> --
> Roger Newson
> Lecturer in Medical Statistics
> Department of Public Health Sciences
> King's College London
> 5th Floor, Capital House
> 42 Weston Street
> London SE1 3QD
> United Kingdom
>
> Tel: 020 7848 6648 International +44 20 7848 6648
> Fax: 020 7848 6620 International +44 20 7848 6620
> or 020 7848 6605 International +44 20 7848 6605
> Email: [email protected]
> Website: http://www.kcl-phs.org.uk/rogernewson
>
> Opinions expressed are those of the author, not the institution.
>
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