All clinical data managers (CDMs) are familiar with the difficulties of ensuring that laboratory values are compared to the local laboratory normal ranges that were valid at the time of the measurement. In studies with many local laboratories, and in global studies, the same test may be reported in different units across the study. To help alleviate these problems, some studies use central laboratories. Yet there are some problems with this approach as well. Shipping samples from study sites to the central laboratory incurs extra cost and runs the risk that the sample will be unusable when it arrives.