Hello,
I'm analyzing a dataset with some nondetectable values (too low and too large) in the outcome variable (log-normally distributed). I know that maximum likelihood estimates of the mean and standard error could be calculated (Hornung, R.W., and L.D. Reed: Estimation of average concentration in the presence of nondetectable values. Appl. Occup. Environ. Hyg. 5:46�51 (1990). Can anybody tell me how to get those estimates using Stata? Also, I need to do a multiple regression analysis with this data. It seems that one way to use the data on subjects with low non-detectable values is to replace them by the limit of detection divided by 2 or by the square root of 2. But, how should I handle high non-detectable values? Any suggestions would be appreciated (including relevant references).
Thanks in advance,
Leonelo E. Bautista, MD, MPH, DrPH
Assistant Professor
Department Preventive Medicine & Biometrics
Uniformed Services University of the Health Sciences
4301 Jones Bridge Road
Bethesda, MD 20814
Room A1039
Phone: (301)2953712
Fax:(301)2951854
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