Because age is a major determinant of mortality, age adjustment, or standardization, is used to compare different populations and geographic areas. With this direct method of standardization, age-specific death rates from two populations — the state public mental health population and the statewide general population — with different age structures can be applied to a third "standard" population. CDC uses the U.S. 1940 standard population for standardizing or adjusting 1997 and earlier years and the U.S. 2000 standard population for 1998 and later years (11-18). This methodology was used for our analyses of public mental health clients so that comparisons could be made with CDC's findings. Clients were divided into 11 age groups: younger than 1 year; 1 to 4 years, 5 to 14 years, 15 to 24 years, 25 to 34 years, 35 to 44 years, 45 to 54 years, 55 to 64 years, 65 to 74 years, 75 to 84 years, and 85 years and older. Age-specific death rates were calculated for each age group of public mental health clients by dividing the number of deaths in that
