Equations Flashcards
prevalence
no. cases of the disease at specific time point/period ////////////// total no. people in the population at same time point/period
risk
all NEW cases of disease in population over specific time period ///////// total population at start of time period
odds of disease
no. new cases of disease //// no. people still disease free
(all in a specified time period)
incidence rate
no. NEW cases of disease in a specified time period //// person-time at risk in that time period
risk ratio
risk in the exposed group
//
risk in the unexposed group
odds ratio of outcome
odds of outcome in exposed group
///
odds of outcome in unexposed group
incident rate ratio
incidence rate in the exposed group
///
incidence rate in unexposed group
attributable risk (AR)
incidence (rate) in exposed - incidence (rate) in unexposed
attributable risk fraction (can express as percentage or decimal)
AR
/////
incidence in exposed group
population attributable risk (PAR)
incidence in whole population - incidence in unexposed group
population attributable fraction (PAF)
PAR
///
incidence in whole population
describe how DIRECT age standardisation works
calculate death rates for each age group in your population
apply these rates to the same age groups in a “standard population”
produces expected deaths for each age group, and can total these to get the DSR (directly standardised rate) per 1000.
e.g. total population = 1000
total expected deaths = 38.5
DSR = 38.5 deaths per 1000 population
describe how INDIRECT age standardisation works
take a set of “standard death rates”
apply these rates to your population
this produces expected deaths per age group
then you get the ratio of observed to expected deaths:
SMR = O/E
(SMR = standardised mortality ratio)
what standardised “thing” do direct and indirect standardisation use?
direct = standard population indirect = standard death rates
odds ratio of exposure
odds of exposure among cases // odds of exposure among controls
