“…The first is much more sophisticated an instrument than the latter and its principles have been described in detail (Wing and Bransby, 1970;Baldwin, 1971). Since it not only avoids selection biases and duplicated counts, but is also based on a defined population and is cumulative over time, it permits a wide range of epidemiological research and facilitates the evaluation and planning of local services (Gardner et al, 1963, Miles andGardner, 1966;Liptzin andBabigian, 1972,Bahn, 1967;Baldwin, 1971;Wing and Hailey, 1972). On the other hand, this type of register has the limitation of being a very costly tech nique, demanding both specialized staff and resources.…”