To take into account the movements of visiters to areas, one has to define extra compartments for each population subdivision to distinguish those who never or seldom visit neighboring areas, the stayers, from those who frequently visit the neighboring areas, the movers. Thus in the home area, the movers and stayers mix and in addition the movers mix in neighboring areas when they are visiting. Such models are called mover-stayer models and are generally considerably more complex than migration models (3,4). Often, the difficulty with using mover-stayer models is that it may be difficult to find adequate data to distinguish visiters and their lengths of stay.