Standardized moality ratio (SMR) The simplest and most useful form of indirect standardization is the Standardized Moality Ratio (SMR). In England, it is the basis for the allocation of government money to the health regions of the country. The concept is That the regions with higher moality also have the higher morbidity, and should therefore receive propoionately higher funding to combat ill-health. Standard moality ratio is a ratio (usually expressed as a percentage) of the total number of deaths that occur in the study group to the number of deaths that would have been expected to occur if that study group had experienced the death rates of a standard population (or other reference population). In other words. SMR compares the moality in a study group (e.g., an occupational group) with the moality that the occupational group would have had if they had experienced national moality rates. In this method, the more stable rates of the larger population are applied to the smaller study group. It gives a measure of the likely excess risk of moality due to the occupation. SMR= Observed deaths /Expected deaths X lOO The SMR has the advantage over the direct method of age adjustment in that it permits adjustment for age and other factors where age-specific rates are not available or are unstable because of small numbers. One needs to know only the number of persons in each age group in the study population and the age-specific rates of the national population (or other reference population). It is possible to use SMR if the event of interest is occurrence of disease rather than death Ref : Park 23rd edition Pgno : 59