How are non-detects factored into the ERMI score?
A. In homes with significant water damage, a wider diversity of the 26 Group 1 species will be detected, while non-water-damaged homes will have more ND or “non-detect” species. For clarification of the ERMI calculation, a “non-detect” is set to a value of 1, since the log of 1 is 0. Therefore, a “non-detect” does not change the ERMI value. It is helpful, then, to look at the results of the analysis for each species and not just the final ERMI value.
