This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
About direct standardization all are true except ? 
Select and explain. 
A. Age specific death rate is not needed, B. A standard population is needed, C. Population should be comparable, D. Two populations are compared
A: Age specific death rate is not needed
Answer: A: Age specific death rate is not needed 
Explanation: Ans. is 'a' i.e., Age specific death rate is not needed Direct standardization Direct standardization is used when the study population is large enough that age specific rates within the population are stable. o Direct standardization is commonly used in repos of vital stastics (e.g., moality) or disease incidence trend (e.g. cancer incidence). o A standard population (reference population) is selected for which the numbers in each age and sex group are known. o Next, age-specific rates of study population (population whose crude death rate is to be adjusted or standardized) are computed. o Then, these age specific rates of study population are applied to standard population (by multiplying these rates by the number of people in that age group in the study population). o These expected rates are summed and divided by the total population size of standard population to yield the directly standardized rates.