  In situations where the sampling units in a study can be more easily ranked
based on the measurement of an auxiliary variable, ranked set sampling provide
unbiased estimators for the mean of a population that they are more efficient
than unbiased estimator based on simple random sample. In this paper, we
consider the Morgenstern type bivariate generalized exponential distribution
(MTBGED) and obtain several unbiased estimators for a parameter mean of the
marginal distribution of MTBGED based on different ranked set sampling schemes.
The efficiency of all considered estimators are evaluate and has also been
demonstrated with numerical illustrations.
