1. introduction to the concepts of measurement and causality in epidemiology Flashcards
What can we estimate from epidemiological studies?
Prevalence of disease
Incidence of disease
Factors associated with the disease
Factors likely to be causally associated with disease
What is the pop of interest known as?
The target population
What is the subset of the target pop?
the study population
Define prevalence
How much of a disease there is in a population at one time
Define incidence
The number of new cases in a time period
What is the relationship between incidence and prevalence?
Incidence = prevalence/duration of infection
What is period prevalence?
The amount of a disease/variable over a defined time period
What is a response/dependent variable and an example?
The variable that is influenced by other variables
Disease occurrence
What is the predictor/independent variable and an example?
The variables that change the response variable
e.g. smoking
What is a risk factor?
A variable that is associated with an increase or decrease in disease
Equation for risk ratio
(a/a+b) / (c/c+d)
Equation for odds ratio
a/b / c/d
When can RR not be measured?
when population exposure is unknown - case control studies
Attributable risk equation
a/a+b - c/c+d
What is the population attributable risk?
attributable risk x prevalence of exposure in population
The amount of disease attributable to an exposure
