Normal Distribution

{
  "id": "MLC-T-ENV-019082",
  "term": "Normal Distribution",
  "field": "Environment",
  "definition": "1. A family of probability density functions whose mean, median and mode are identical. The function generates a symmetrical curve, whose position and shape is determined by its location and scale parameters, the mean and standard deviation respectively. The standard normal distribution has a location parameter of 0 and a scale parameter of 1.\n\n2. Distribution of data points with most values close to the center or norm, and fewer and fewer occurring as we move further and further out from the norm. If a particular data set closely fits a normal distribution curve, the implication is that nothing is going on in that situation except random variation around a norm. [Brooks 2001]\n\n3. Continuous frequency distribution of infinite range. Its properties are as follows: (1) continuous, symmetrical distribution with both tails extending to infinity; (2) arithmetic mean, mode, and median identical; and (3) shape completely determined by the mean and standard deviation. [CancerWeb 2005]\n\n4. Symmetrical clustering of values around a central location. The properties of a normal distribution include the following: (1) It is a continuous, symmetrical distribution; both tails extend to infinity; (2) the arithmetic mean, mode, and median are identical; and, (3) its shape is completely determined by the mean and standard deviation. [CDC 2005]\n\n5. A unimodal symmetrical (bell-shaped) distribution where the most prevalent value is the mean (average) and the spread is measured by the standard deviation. Mathematically, the distribution varies from minus infinity with zero probability to plus infinity with zero probability.\n\n6. A symmetric distribution with one high point or mode, sometimes also called the bell curve. The average is one of many statistical calculations that, even for only a moderate amount of data, tend to have a distribution of that resemble the normal curve. [NIST/SEMATECH 2005b]",
  "references": [
    "National Cancer Institute Thesaurus",
    "Thesaurus of Terms Used in Microbial Risk Assessment",
    "Benchmark Dose Software (BMDS) Glossary of Terms"
  ],
  "url": "https://mlchart.com/terminology/environment/normal-distribution/"
}