SVIB revisions and factors affecting scale reliability

The 1966 SVIB scoring keys were investigated and found to contain an average of 214 fewer items per occupational scale than the 1938 scoring keys. The shorter scales are less reliable than the longer scales on the 1966 SVIB. The shorter scales in the 1966 edition and SCII contain items which differentiate criterion group members less well than do the longer scales. There may not be a wide enough range of item content on the SCII to develop reliable (and valid?) scales for certain occupations. Equivalence between the 1938 and 1966 editions functionally is low, as evidenced by the median correlation of .47 in the present 12-yr follow-up study for 40 occupational scales.