Standardisation (mortality)
Contents 
Mortality rates
 Deaths per year divided by estimate of people alive during that year.
 Usually per 10,000
 Crude mortality rate, vs eg

 Causespecific mortality rate
 Ageadjusted standardised mortality rate
 Age/gender/ethnicityspecific mortality rate
Crude mortality rate
 Very easy to calculate
 Deaths per 10,000 popn per year
 Useful in crises as crude measure

 >1/10,000 per year is an emergency
 Rates of about 3 observed in Dafur
Standardisation
 Standardisation is used to remove the effect of [an] unwanted variable[s] such as age and/or sex from a comparison between two populations.small numbers
 Methods of comparing study population with wider population
 Means of judging external validity
 Direct standardisation is used whenever stratumspecific rates are available
 Indirect standardisation is used when stratumspecific rates are unavailable or unstable because of
Direct standardisation
 Calculate the agespecific rates for study population.
 Take number of people in those age groups in standard population, and calculate the rate that would apply to that population, if the agespecific rates in the study population applied.
 Gives a RATE.
Indirect standardisation
 Take the number of deaths in the study population.
 Take the agespecific rates for the standard population, and calculate the number of deaths that would be expected in the study population if the standard rates applied (by multiplying the standard rates by the number of people in age group in the study population)
 Divide the actual rates by the expected rates, and multiply by 100.
 Gives a RATIO.