Probability Sample

{
  "id": "MLC-T-ENV-022220",
  "term": "Probability Sample",
  "field": "Environment",
  "definition": "1. A group of cases selected from a population by a random process. Every member of the population has a known, nonzero probability of being selected.\n\n2. A probability sample is a sample where every element of the target population has a known, non-zero probability of being selected. That is, it is possible for every element of the target population to be in the sample. Two important features of a probability sample are that the probability selection mechanism (1) guards against site selection bias and (2) is the basis for scientific inference to characteristics of the entire target population. See: Probability Sample FAQ (http://www.epa.gov/nheerl/arm/surdesignfaqs.htm#whatprobabilitysample).\n\n3. A sample chosen in such a manner that the probabilities of including the selected units in the sample are known, and all population units have a positive probability of selection. This implies that the target population is represented by the sample and that the target population is explicitly defined.\n\n4. Sample where every element of the target population has a known, non-zero probability of being selected. That is, it is possible for every element of the target population to be in the sample. Two important features of a probability sample are that the probability selection mechanism (1) guards against site selection bias and (2) is the basis for scientific inference to characteristics of the entire target population.\n\n5. Sample chosen in such a manner that the probabilities of including the selected units in the sample are known, and all population units have a positive probability of selection. This implies that the target population is represented by the sample and that the target population is explicitly defined.",
  "subject": "Policy and guidance",
  "references": [
    "Program Evaluation Glossary",
    "Aquatic Resource Monitoring - Terminology",
    "Environmental Modeling and Assessment Program (EMAP) Master Glossary",
    "EMAP Master Glossary"
  ],
  "url": "https://mlchart.com/terminology/environment/probability-sample/"
}