Maybe a dumb question, but I just started, so thanks for any help.
I created 99% confidence interval for a proportion, but I'm not sure if it is correct, how can I make sure, (when we're calculating confidence interval for mean, we're using t-score, and we can test the results by using t.test function and degrees of freedom)
Is there any similar function to do the same thing for z, proportions? or I can do the same thing by using t.test?
There are a number of functions in R for computing confidence intervals for proportions. Personally, I like to use the binomCI function from the MKinfer package:
install.packages("MKinfer")
library(MKinfer)
x <- 50 # The number of "successes" in your data
n <- 100 # The number of observations in your data
binomCI(x, n, conf.level = 0.99, method = "wald")
Note however that the so-called Wald interval (which is presented in most introductory texts on statistics) that you probably computed usually is a poor choice. See this link for some other alternatives available through binomCI.