5.7 Estimand, estimator and estimation

• Estimand: Parameter in the population which is to be estimated in a statistical analysis
• e.g. mean age of the Swiss population
• Estimator: A rule for calculating an estimate of a given quantity based on observed data
• e.g. formula to calculate mean age in a (random) sample of the Swiss
• Estimate: e.g. actual mean age we calculated based on the sample
• Estimation:
• The process of finding an estimate, or approximation, which is a value that is usable for some purpose even if input data may be incomplete, uncertain, or unstable (value derived from the best information available)
• Rule (the estimator), the quantity of interest (the estimand) and its result (the estimate) are distinguished.