Ferguson (2010) conducted an updated meta-analysis largely confirming the findings of Roberts and DelVecchio (2000). His analysis emphasized the importance of correcting stability coefficients for measurement error of the indicators. Measurement error is by definition unsystematic and therefore unable to be correlated across time points. Measurement error attenuates the true amount of stable variation in personality. Ferguson’s (2010) estimated stability coefficients peaked and plateaued in early adulthood, but at a much higher level that approximated a “set in plaster” limitation of personality change (e.g., r12 = .94 for age 28–34). Measurement error may pose special problems for research on the stability of personality if assessment inventories differ in reliability across different age groups.
