ABSTRACT
In the bulk of the material covered up to this point it was implied, if not stated, that the probability of a sampling unit being drawn in a sampling operation was constant for all the sampling units in the sampling frame. It was recognized, of course, that where the sampling frame is finite in size and the sampling is without replacement, the probabilities change from draw to draw but within a draw all the available sampling units have the same probability of being drawn. Now consider the situation where all of the sampling units do not have the same probability of being drawn.
