Other things being equal, the longer the retest interval, the lower
the stability coefficients. In Table 12, a study by Leon et al. (1979) is re -
ported. Here the same individuals were retested twice, once after 13
years, and again after another 17 years. The median stability coefficientafter 13 years was .50; across the whole 30-year interval it was only .40.Our own studies of the GZTS continued after the 12-year study re -
ported in Table 9; by 1992 we had GZTS data over a 24-year period. The
median 12-year stability was .74, whereas at 24 years the median stabil -
ity coefficient had declined to .65—still amazingly high, but clearly
lower. This generalization is supported by a meta-analysis (a quantita -The Course of Personality Development 113
TABLE 13. Stability of NEO-PI Scales for Younger and Older Men
and Women
Age 25–56 years Age 57–84 years
NEO-PI scale Men Women Men Women Total
Neuroticism .78 .85 .82 .81 .83
Anxiety .74 .72 .72 .75 .75Hostility .74 .74 .75 .72 .74Depression .62 .77 .71 .66 .70Self-Consciousness .74 .81 .79 .78 .79Impulsiveness .66 .65 .70 .67 .70Vulnerability .73 .76 .60 .75 .73
Extraversion .84 .75 .86 .73 .82
Warmth .74 .66 .74 .66 .72Gregariousness .76 .69 .76 .68 .73Assertiveness .73 .75 .84 .79 .79Activity .72 .74 .77 .74 .75Excitement Seeking .69 .61 .79 .63 .73Positive Emotions .80 .65 .69 .69 .73
Openness .87 .84 .81 .73 .83
Fantasy .77 .74 .69 .63 .73Aesthetics .75 .83 .81 .67 .79Feelings .72 .61 .64 .62 .68Actions .75 .73 .66 .58 .70Ideas .78 .84 .78 .75 .79Values .77 .69 .70 .67 .71
Agreeableness .64 .60 .59 .55 .63Conscientiousness .82 .84 .76 .71 .79
Note. All correlations are significant at p< .001. N’s = 63 to 127 for subsamples. Retest interval is 6
years for N, E, and O; 3 years for short A and C scales. Adapted from Costa and McCrae (1988b).