Lee WC, Sinha SK, Arbuckle TE, Fisher M. Statistics in Medicine. 2018 Aug 30. doi: 10.1002/sim.7942.
The laboratory method to measure concentrations of various chemicals in blood or urine has what is termed a “detection limit”, which is a minimum amount that can be measured. Therefore, it is not unusual that there will be some lab results that fall below this detection limit. These lab results could be anywhere between “0” and the detection limit. There has been much discussion among researchers on how to consider any results below the detection limit when they do statistical analyses of the data.
This study proposed one method for dealing with this problem and then investigated how different chemical mixtures affect the health outcomes of infants and pregnant women, using data from the MIREC study.