Which analytical parameter is often expressed using a geometric mean?

Total coliform is often expressed using a geometric mean because this statistical measure is particularly useful for data that is positively skewed and for dealing with values that may span several orders of magnitude. In the context of water quality monitoring, total coliforms are analyzed for their presence in water samples that may include a mix of very low and very high counts. The geometric mean offers a more accurate representation of the central tendency of these counts when compared to the arithmetic mean, especially in cases where many samples may have no detectable coliforms (which would skew the average if calculated arithmetically).

Using the geometric mean provides a more reliable assessment of microbial safety, as it allows for a better understanding of the overall level of coliform bacteria in a series of samples over time. Regulatory standards often use the geometric mean for coliforms to determine compliance with health standards, as it reflects a more consistent level of contamination rather than being overly influenced by extreme outlier values, which could misrepresent water quality.

This reasoning underscores the relevance of the geometric mean specifically for total coliform analysis in wastewater treatment and environmental monitoring.