Statistics Seminar: Ganes S Ganeslingam (Massey University) -- Ranked Set Sampling versus Simple Random Sampling in the Estimation of the Mean and the Ratio

It is common in practice that the experimental units can be 
ranked easily using a cheaply measurable covariate than 
quantification of the main variable of interest which requires
expensive measurements.  In such situation ranked set sampling
is more beneficial and cost effective. Environmental monitoring 
and assessment, for example, requires observational data where 
the ranked set sampling is proved to achieve observational 
economy when compared to the traditional simple random sampling. 
Ranked set sampling employs judgment ordering to obtain the 
actual sample and hence yield a sample of observations that is 
more representative of the underlying population.  Therefore, 
either greater confidence is gained for a fixed number of 
observations, or for a desired level of confidence, a smaller 
number of observations is needed.  In either way it is a big 
gain to the researcher. In this paper, we introduce the basic 
concepts of ranked set sampling and its application in the 
estimation of the population mean.