Ratio Estimation of Population Total

Ratio estimation can be used to improve the efficiency of the estimation of T, if a continuous auxiliary variable z is available. The population total Tz and the n sample values zk of z are required for this method. This information can be used to improve the estimation of T by first calculating the sample estimator of the ratio R = T/Tz and multiplying it by the known total Tz. Ratio estimation of the total can be very efficient if the ratio Yk/Zk of the values of the study and auxiliary variables is nearly constant across the population. Ratio estimators are usually effective but slightly biased. See pages 93-95 in Lehtonen, R & Pahkinen, E. (2004)

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