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Unformatted text preview: was less than 5% (i.e., we used a 95%
Rank-order stability was assessed by the correlation between Week 1 and
Year 4 personality scores.
To test the structural stability of the Big Five, we used structural equation
modeling to compare the fit of two models, one in which the intercorrelations
among the Big Five were freely estimated at each time point and the other in
which the intercorrelations among the Big Five were constrained to be equivalent across the two assessments. A significant difference in fit between these
two models would indicate that there was significant change in the structural
relations among the Big Five.
To assess ipsative stability over time, we computed three indices of profile
similarity. Cronbach and Gleser (1953) observed that individual profiles can
vary in three ways: elevation (the average level of scores), scatter (the
variability of scores), and shape (the patterning of scores, or relative salience
of the Big Five within a profile). Cronbach and Gleser outlined three methods
for quantifying these sources of variability. The first index, D2, quantifies the
3. The RC index is based on classical test theory and thus makes a number of assumptions
that may or may not be valid (e.g., error variance is constant across participants and over
time). To the extent that these assumptions do not hold in the present data, our estimates
of how many individuals increased, decreased, and stayed the same may be biased. 626 Robins et al. squared differences between trait levels at two time points, summed across all
five traits. D2 is sensitive to differences in elevation, scatter, and shape. The
second index, D′2, quantifies the squared differences between profiles after each
profile has been centered around its mean. D′2 is insensitive to differences in
mean levels between profiles and only reflects differences in scatter and shape.
The third index, D″2, quantifies the squared differences between profiles after
each profile has been standa...
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- Fall '10