# [R] Coefficients, OR and 95% CL

Eik Vettorazzi E.Vettorazzi at uke.uni-hamburg.de
Tue Sep 23 14:29:21 CEST 2008

```l.mod<-glm(menarche~age,binomial)

you will get odds-ratios by exponentiating the coefficients of this
model, so

exp(coef(l.mod))

will do this job. You may notice that this will produce an "OR" for the
intercept part as well - which is not interpretable.
For the confidence intervals for this odds ratio you have to
exponentiate the borders of the "standard" confidence intervals for the
log-odds-ratios,

exp(confint(l.mod))

hth.

Luciano La Sala schrieb:
> Dear R-users,
>
> After running a logistic regression, I need to calculate OR by exponentiating the coefficient, and then I need the 95% CL for the OR as well. For the following example (taken from P. Dalaagard's book), what would be the most straightforward method of getting what I need? Could anyone enlight me please?
>
> Thank you!
> Lucho
>
>
>> summary(glm(menarche~age,binomial))
>>
>
> Call:
> glm(formula = menarche ~ age, family = binomial)
>
> Deviance Residuals:
>      Min        1Q    Median        3Q       Max
> -4.68654  -0.13049  -0.01067   0.09608   2.35254
>
> Coefficients:
>             Estimate Std. Error z value Pr(>|z|)
> (Intercept) -17.9175     1.7074  -10.49   <2e-16 ***
> age           1.3549     0.1296   10.45   <2e-16 ***
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>
> (Dispersion parameter for binomial family taken to be 1)
>
>     Null deviance: 974.31  on 703  degrees of freedom
> Residual deviance: 223.95  on 702  degrees of freedom
>   (635 observations deleted due to missingness)
> AIC: 227.95
>
> Number of Fisher Scoring iterations: 9
>
>
>
>
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> and provide commented, minimal, self-contained, reproducible code.
>

--
Eik Vettorazzi
Institut für Medizinische Biometrie und Epidemiologie
Universitätsklinikum Hamburg-Eppendorf

Martinistr. 52
20246 Hamburg

T ++49/40/42803-8243
F ++49/40/42803-7790

```