Basic Health Terms and Statistics
What is the difference between a rate and a proportion?
Proportion: Is the fraction of the population is affected by a disease. Proportionate mortality is a
commonly used proportion in epidemiology and provides the proportions of death that is caused
by a specific disease. For example 30% of deaths in Canada in 2004 were caused by cancer.
= number of deaths attributed to a disease in a population during a specified yearX 100
Number of deaths in the same population and year
Rates: Tell us how fast the disease is occurring in a population. So, there is a time period that
must be considered. The time period is arbitrary i.e. month, year(s). Some examples of rates
include; crude mortality, incidence and prevalence rates.
The occurrence of illness or diseases and is calculated with the population at risk or person-time,
if people at risk is observed for different period of times.
Incidence and prevalence are the two measures of morbidity.
Incidence: Number of new cases
What are the two measures of morbidity? Provide the equations
What is the crude mortality