[R] help with OR confidence interval using probit link

Rosa Oliveira rosita21 at gmail.com
Thu Apr 14 20:11:36 CEST 2016

Howdy everyone

I’m trying to get Odds ratio and OR confidence intervals using a probit model, but I'm not getting.

Do you think you can help me?

I’m new with R L

naive                   = summary(glm(pcr.data[,7]~boldBeta_individual+pcr.data$age,family=binomial(link=probit)))

naive_answer            = c(naive$coefficients[,1:3])                           #naive estimates for

                                                                                #alpha (first 4 collumns: intercept; beta_intercept, beta_slope and age) and 

                                                                                #and SE(last 4 collumns: intercept; beta_intercept, beta_slope and age)

OR.naive = exp(1.6*coef(naive))

(till here works, the problem is with the confidence interval)

I tried to get the Standard error from the variance, but I’m not sure if this can be done as I’ve done.

Var_coef <- 1.6^2*var(coef(naive))

SE_coef <- Var_coef/sqrt(nsample)                    ########## I thi k this is correct

OR.naive.inf <- exp(OR.naive - (1.96 * SE_coef))

OR.naive.sup <- exp(OR.naive + (1.96 * SE_coef))

if I used logit link I would get the CI with confint(naïve) command, but with probit I don't think so. Is there a way?

What should I do?

Rosa Oliveira


Rosa Celeste dos Santos Oliveira, 

E-mail: rosita21 at gmail.com <mailto:rosita21 at gmail.com>
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