Parameter

Values that summarize properties of the population are known as parameters. Commonly expressed parameters are the population mean (greek letter mu) and the population variance (greek letter sigma2).

Each population has a unique set of parameters, but their actual values are rarely known because of the impracticality of taking a census that includes every member in the population. Instead, data obtained from sampling is used to infer information regarding the parameters of the population.

We need a simple understanding of population parameters in rangeland inventory or monitoring for two reasons:

  1. The objective of a sampling program is to estimate the parameters without measuring every member of the population.
  2. Statistical techniques to analyze differences between treatments, sites, years, etc., are based on comparing parameters from different samples to determine the probability that all data from these different locations and sampling dates are actually derived from the same population.

References and Further Reading

Bonham, C.D. 1989. Measurements for terrestrial vegetation. John Wiley Son, New York, NY. pp 50-58.

Cochran, W.G. 1977. Sampling techniques. John Wiley Sons, New York, NY.