does correlation of before and after data always apply to the same group of subjects is it ok to correlate before and after data when correlated before and after data is not always correct is it ok for before and after data to be correlated with prior data when is it ok to correlate do correlation coefficients need to be used in before and after data when are before and after blood tests correlated is it ok to correlate before and after data can you correlate a group of data before and after surgery? can you correlate before and after data is it ok to correlate before and after data? is it ok to correlate before and after data? is it ok to correlate before and after results why is correlation not good before and during a patient visit is it ok to correlate before and after is it ok to correlate before and after data when you perform correlations before and after data is it ok what is the correlation between before and after should you correlate before and after data can you correlate data before and after