Evidence for the construct validity of the Sentence
Completion Test of Ego Development (SCT),
some of it previously unpublished, is reviewed. The
substantive component is substantiated both by intuitive
plausibility and by the fact that rating skill
can be communicated through written instructions.
Internal consistency is shown by alpha coefficients
of about .85. Evidence for sequentiality is provided
by studies showing cross-sectional gains with age
during adolescence, similar profiles of item scores
for adjacent total protocol ratings, substantial correlations
over long time spans, gains proportional
to retest intervals during adolescence, gains following
theory-relevant interventions of several months’
length, and better comprehension of lower than of
higher stages. The SCT has substantial correlation
with tests of related conceptions, such as Kohlberg’s
test of moral maturity, and with measures of
ego level applied to other behavior samples. Correlations
with isolated traits characteristic of specific
stages range from negligible to positive.
Studies of external validity in general yield positive
results, though theory does not sharply define what
results should be considered positive. At lower ego
levels there is behavioral evidence confirming the
syndromes; at higher levels differential evidence lies
in attitudes and ideas. Overall, the test has adequate
validity for research purposes when administered
and scored with sufficient care, but not
for individual diagnosis unsupported by other data.
Evidence for construct validity is substantial, but
falls short of clear proof of sequentiality.