What is a geometric mean?

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Multiple Choice

What is a geometric mean?

The geometric mean is used as a central measure for data that are multiplicative or highly skewed, such as bacterial counts in water. To compute it, multiply all the sample values together and take the nth root (where n is the number of samples); equivalently, log-transform each value, average those logs, and exponentiate the result. In recreational water testing for E. coli, counts can vary greatly from sample to sample, so the geometric mean provides a representative “typical” level that minimizes the influence of extreme high values. This is the standard way to summarize average bacterial levels across beach samples to assess compliance with public health guidelines. It’s not the maximum value, nor the median one would use for other data sets, nor a simple pH average.

The geometric mean is used as a central measure for data that are multiplicative or highly skewed, such as bacterial counts in water. To compute it, multiply all the sample values together and take the nth root (where n is the number of samples); equivalently, log-transform each value, average those logs, and exponentiate the result. In recreational water testing for E. coli, counts can vary greatly from sample to sample, so the geometric mean provides a representative “typical” level that minimizes the influence of extreme high values. This is the standard way to summarize average bacterial levels across beach samples to assess compliance with public health guidelines. It’s not the maximum value, nor the median one would use for other data sets, nor a simple pH average.

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