Residuals

In statistics in general, the concept of residuals (e) is used when referring to the observable deviation of an individual observation in a sample to its corresponding sample mean. Not to be confused with the statistical error (ε), which refers to the often unobservable deviation of an individual observation from its often unknown population mean. The residual serves as an estimate for the unobservable statistical error when a sample is drawn from the population of interest but the population mean cannot be computed because the researcher simply does not have all individual observations belonging to the target population.

In this entry, the concept of residuals in regression analysis is defined, the use of residuals for checking the standard regression assumptions is discussed, and the role of ...