r - Variance with vlm probit -

i implementing model logit. how can variance of data measure if prediction variance of data measure if prediction enter code here or not?

m <- glm(a~ f+ en*rt, family = binomial(link = "logit"),data=df)` 

i read can did this, using confidence intervals:

p <- predict(m, newdata=df, type="link",se.fit = t) critval <- 1.96 ## approx 95% ci upr <- p$fit + (critval * p$se.fit) lwr <- p$fit - (critval * p$fit) fit <- p$fit mean(((upr-fit)/1.96)^2, na.rm=t) 

but values huge. appreciate help.