Indirect standardisation biostatitics

Indirect standardisation biostatitics

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  INDIRECT STANDARDISATION Dr. Rinsa Vaheed
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  What is Standardization? In statistics, standardization is a process of putting different variables on the same scale  Process allow you to compare scores between different types of variables 2 methods of standardisation 1. Direct (used in population distribution) 2. Indirect (set of specific rates)  Age is the factor that frequently adjusted in epidemiological investigation….it affects the populations overall mortality
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  INDIRECT METHOD  Itis used to study mortality in occupationally exposed population  Requires the knowledge of the age and sex structure of the population as well as the age specific rates of events under consideration for the standard population  Used when the number of death for each age specific stratum is not available
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  Indirect Standarisation
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  Indirect Standarisation  Steps: Step 1: choose a reference or standard population  Step 2: calculate the observed number of deaths in the population of interest  Step 3: apply age-specific mortality rates from the chosen population to the population of interest
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   Step 4:multiply the number of people in each age group of the population of interest by the age-specific mortality rate in the comparable age group of the reference population  Step 5: sum the total number of expected deaths for each population of interest  Step6: divide the total number of observed deaths of the population of interest by expected deaths
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   The simplestand most useful form of indirect standardisation  Obtained when observed events are divided by expected events SMR =observed number of death x100% Expected number of death
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  ISSUES IN THEUSE OF STANDARDISTION  It is used for the comparison of two or more population  Indirect method requires total number of cases  Indirect standardization is more appropriate …study done in small group or when rates are unstable  Affect the comparison between population…should state clearly which SP has been applied  Standardization is used to adjust the effect of a variety of confounding factors eg: age, sex
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  Thank you