The second step in the analysis was to define each of the factors that are included in the ADS and to specify certain options in MAS that determine how age and calendar year are represented. In the facility comparison analyses age-related effects were implicitly represented through the use of the external rates, and calendar period was included as a factor in the analysis. The resulting ADS ( see Table AI ) contained data for each of the maximum possible 180 cells where the person-years are greater than zero and a separate ADS was generated for each race and gender group. For example, for white males there were 175 cells and the observed deaths and SMRs for each cause are listed in Table III. The expected deaths were obtained using rates for the U.S. population, , i.e. the expected deaths in each cell are , where is the person-years in the age group of the stratum and is the age-cause-specific death rate for the appropriate U.S. race and gender group.