Key points are not available for this paper at this time.
Strides forward in theory development were achieved by Hardy (1964), Reiss (1967, 1970a, 1970b), Christensen (1969), and Burr (1970). In the Reiss (1967) and Christensen (1969) studies propositions and theory were developed from empirical studies. Subsequent testing of some of Reiss' propositions have suggested that increased care needs to be exercised in the design of research to basically give adequate opportunity for the propositions to be tested under suitable conditions. Burr (1970) gives promise of making a very important contribution through further development of some of the propositions developed by Reiss (1967) and by Christensen (1969), and restating them in such a way as to increase their precision and clarity, so that they can be tested and expanded more readily.
Cannon et al. (Mon,) studied this question.