All are true regarding direct standardization except:

Without knowledge of the composition , the two population can be compared Standardization is carried out by one of the method direct or indirect standardization. Both the method being by choosing a standard population. 1st step : Standard population is selected (standard population is defined as one for which the number in each age and sex group are known). It means age composition are known. 2nd step : Age specific rate is applied on standard population whose crude death rate is to be adjusted or standardized. As a result for each group an excepted number of death ( or event) in the standard population is obtained, these are added for all age group to give the total expected death. Finally : Divide the excepted total number of death by the total of the standard population. This yield standardized or age adjusted rate. Without removing confounding factor (age, sex etc.) two population can't be compared for this reason age composition is required. Note: vital statistics ( death rate, bih rate etc.) is required for direct standardization.