Lecture 2.1: Comparing Populations- Standardisation Flashcards
Point Prevalence Calculation
No. Cases at a Single Point in Time/No. Persons in Population at Same Time Point
Incidence Rate Calculation
No. New Cases During Time Period/(Total Population x Time)
How Are Prevalence and Incidence Measured? (2)
- Routine Surveillance
- Population Samples
What is Standardisation?
A set of techniques used to remove as much as possible the effects of differences in age or other confounding variables when comparing two or more populations
Target Population(s) Definition
The population(s) that we are interested in
Standard Population(s) Definition
The population that we use to construct comparisons with and between target populations
Crude Mortality Rate (per 1000)
(Total No. Deaths/Total Pop Size) x 1000
How to Choose a Standard Population?
- Choose a population that is relevant to the target
populations - If a relevant standard population doesn’t exist
you can make one up by pooling data
What is Prevalence?
Refers to proportion of persons who have a condition at or during a particular time period
What is Incidence?
Refers to the proportion or rate of persons who develop a condition during a particular time period
Age-Specific Deaths (per 1000) Calculation
(Number of Deaths in Age Group/ Number of Persons in Age Group) x 1000
Directly Standardised Mortality Rate
[Ʃ(% of Pop in category x Age Specific Death Rate + % of Pop in category x Age Specific Death Rate +…)]/100
Absolute Expected Deaths (by age) Calculations
(Absolute Target Age’s Group Population Size x Standard Age-Specific Death Rate) /1000
Standardised Mortality Ratio Calculation
Observed Deaths/Expected Deaths
