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a weighted average of stratum-specific rates a weighted average of stratum-specific rates with the weights coming from the distribution of a standard population with the weights coming from the distributions of the study populations to each stratum of your study population to each stratum of a standard population THE RESULT from the standard population from each exposure group in your study population Apply stratum-specific rates Apply stratum-specific rates INDIRECT ADJUSTMENT DIRECT ADJUSTMENT

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Direct Adjustment Indirect Adjustment Exposure (E, city), outcome (D, pregnancy) and a confounder (C, age) Exposure (E, city), outcome (D, pregnancy) and a confounder (C, age) For each city (E), the rates of pregnancy (D) by age group (C) are known For at least one city (E), the rates of pregnancy (D) by age group (C) are unknown Create a standard population (e.g. add populations of City A and B by age category) For each city and each age group: multiply pregnancy rate * the number in age
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Unformatted text preview: group in standard population =the number pregnancies by age group that would occur in each city if age was distributed like the standard population • For each city, add the number of pregnancies and divide by total population number in standard population • Choose a standard population with known pregnancy rate by age group (City A) • Multiply rates from City A (standard population) * number of people in each of City C’s age categories = the expected number of women that would be pregnant by age group in City C if the rates were the same as City A by age category • Calculate SMR = Total number of observed pregnancies in City C/Total number of expected in City C • Multiply SMR * crude rate in standard population (City A) Result: adjusted rate for both City A and City B to compare (specific to standard population) Result: adjusted rate for City C that you can compare to crude rate of City A...
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