Geometric Mean

{
  "id": "MLC-T-ENV-012264",
  "term": "Geometric Mean",
  "field": "Environment",
  "definition": "1. The nth root of the product of n values.\n\n2. The nth root of the product of n observations. For lognormal distributions, the GM is equal to the median and is less than the arithmetic mean. For normal distributions, all three measures of central tendency (GM, AM, median) are equal.\n\n3. The nth root of the product of n values. [EPA 1997a]\n\n4. A measure of central tendency. Calculable only for positive values. It is calculated by taking the logarithms of the values, calculating their arithmetic mean, then converting back by taking the antilogarithm. [Last 1983]\n\n5. Mathematical average calculated by taking the average of log-transformed data; often used to describe data sets that are notnormally distributed.\n\n6. The nth root of the product of n numbers; the same as the antilog of the mean of the logarithms. Tends to be a better measure of central tendency for skewed distributions, but is zero if any datum is zero. Estimates the geometric mean of a lognormal distribution, but with some bias (which can be corrected). (NZ 2002)",
  "abbreviation": "GM",
  "subject": "Health and safety",
  "references": [
    "Exposure Factors Handbook: Glossary; EPA 1997a",
    "EPA Definitions of Terms Relevant to PRA and References for Further Reading at http://www.epa.gov/oswer/riskassessment/rags3adt/pdf/appendixe.pdf",
    "Thesaurus of Terms Used in Microbial Risk Assessment",
    "National Biomonitoring Program Glossary"
  ],
  "url": "https://mlchart.com/terminology/environment/geometric-mean/"
}