The modified Global Assessment of Functioning (GAF) scale has more det
ailed criteria and a more structured scoring system than the original
GAF. The two scales were compared for reliability and validity. Raters
who had different training levels assigned hospital admission and dis
charge GAF scores from patient charts. Intraclass correlation coeffici
ents for admission GAF scores were higher for raters who used the modi
fied GAF (0.81), compared with raters who used the original GAF (0.62)
. Validity studies showed a high correlation (0.80) between the two se
ts of scores. The modified GAF also correlated well with Zung Depressi
on scores (-0.73). The modified GAF may be particularly useful when in
terrater reliability needs to be maximum and/or when persons with vary
ing skills and employment backgrounds--and without much GAF training--
must rate patients. Because of the increased structure, the modified G
AF may also be more resistant to rater bias.