[R] probit analysis for correlated binary data

[Law, Jacqueline {Regu~Pleasanton}]

Dear all,

I have a question on the dose-response estimation with clustered/ correlated binary data.
I would like to estimate the hit rate for a certain test at various concentration levels. The test is used
on 5 subjects, and each subject is tested 20 times. If we assume that the 100 samples are 
independent, the hit rate estimate is unbiased, but the variance is under-estimated. The other
estimate of interest is the concentration that will give a 95% sensitivity of the test. I suppose the
same problem would occur if a probit model is fitted to the data and assume all the samples are
independent. Does anyone have any suggestions on how to analyze this kind of data? 

Thanks a lot in advance.

- Jacqueline