Hello, R exits every time I want to fit a GEE with AR-1 correlation structure. It just closes itself without any error. My Data has about 3300 observation (using the big data with about 20 000 observation it doesn't work at all). I'm a Windows 2000 User of R 2.0.1 but it was the same problem on a MacOSX. Is it my fault? Thank you for your help! Johanna Brandt