Key points are not available for this paper at this time.
George St. J. Perrott, Clark Tibbitts, Rollo H. Britten, The National Health Survey: Scope and Method of the Nation-Wide Canvass of Sickness in Relation to Its Social and Economic Setting, Public Health Reports (1896-1970), Vol. 54, No. 37 (Sep. 15, 1939), pp. 1663-1687
Perrott et al. (Sun,) studied this question.