st: Re: tabulate

[Roger Newson <roger.newson@kcl.ac.uk>]

At 17:18 26/01/04 +0100, Elisa wrote:
> Why can't one use chi2 (or all in general) command with tabulate and weight?
>
>      tabulate var1 var2 [aweight=divwt], chi2
>
> the error in this case is:
>
>      option chi2 not allowed
You should have used -fweight- instead of -aweight-. See -[R] weight- or 
online help for -weight-. As in this example:

. tab rep78 foreign [fwei=mpg], chi

    Repair |
    Record |       Car type
      1978 |  Domestic    Foreign |     Total
-----------+----------------------+----------
         1 |        42          0 |        42
         2 |       153          0 |       153
         3 |       513         70 |       583
         4 |       166        224 |       390
         5 |        64        237 |       301
-----------+----------------------+----------
     Total |       938        531 |     1,469

          Pearson chi2(4) = 570.7234   Pr = 0.000

-fweight- specifies frequency weights. Here, we assume that each model is 
represented in the original sample by a number of cars equal to -mpg-, 
presumably because cars that do more miles per gallon are more popular.

I hope this helps.

Roger


--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
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Tel: 020 7848 6648 International +44 20 7848 6648
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Email: roger.newson@kcl.ac.uk
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Opinions expressed are those of the author, not the institution.

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