This is a possibility that can occur with the type of lab tests that Battelle is conducting, which is a cell-based assay. For each material studied, five samples are inoculated with the virus and examined at each time point. At levels below LOQ (the limit of quantitation), the Battelle researchers simply record a positive or negative to indicate either presence or lack of presence of virus, not the actual number of virus particles. This is a qualitative assessment based on observation through a microscope: the researchers look at each of the five samples and record whether they see any virus; the resulting number is an average across those five samples. When the infectious virus load starts at a very high level (i.e., up to 100,000 particles), the difference at the low end of 1 or none can be somewhat variable.