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# Re: st: Spline after Cox regression

 From Nick Cox To "statalist@hsphsun2.harvard.edu" Subject Re: st: Spline after Cox regression Date Fri, 5 Jul 2013 21:28:55 +0100

```How many distinct values does -lnffa- have? Was that the variable you
meant to use?
Nick
njcoxstata@gmail.com

On 5 July 2013 21:23, Etan Lakam <etan.lakam@googlemail.com> wrote:
> Dear Listers,
> I am doing Cox-regression with a continuous exposure ffa and the
> outcome hf, I have been trying to model it as  cubic spline.
> Here is how I approached it, adjusting for age, sex, and race, however
> it is coming up with the message error below, and I cannot obtain the
> graph
> I do not have a clue about what is happening.
> Best,
> Etan
>
>
> mkspline  rlnffa= lffa, cubic nknots(5)
> stcox rlnratio* sex race age
> adjust race=0 sex=1 age, by(lnffa) ci replace exp
> ------------------------------------------------------------------------------------------
>      Dependent variable: _t     Command: stcox
>    Variables left as is: rlnffa1, rlnffa2
>   Covariate set to mean: age = 53.900191
> Covariates set to value: race = 0, sex = 1
> ------------------------------------------------------------------------------------------
> too many values
> r(134);
> *
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```