The GZTS scales are valid and reliable (38). Internal consistency coefficients range from .75 to .87 (Mdn = .80)(38). In the BLSA, the structural stability of the GZTS has been shown across age, cohort, and time-of-measurement (43). Retest stability coefficients for men ranged from .64 to .78 (Mdn = .68) over an average interval of 16 years, and retest coefficients for women ranged from .68 to .78 over an average of interval of 11 years (Mdn = .71)(44).
