Week 3 - Incidence + Prevalence Flashcards
What is a rate?
a number tha reflects the cases present in a population
What pieces of information do you needs to calculate a frequency?
- the number of cases
- the size of the population at risk
- the period during which we are calculating the rate
What is the population at risk?
The people who are susceptible to a disease
What is the prevalence rate?
the frequency of existing cases in a defined population at a given point in time
What is the incidence rate?
the rate at which new cases occur in a given period of time in a specified population
what is the formula for frequency?
number of cases / population at risk * 100
What is the numerator in the prevalence formula?
the number of existing cases of disease during a specified time period
what is the formula for the prevalence rate?
number of existing cases / the population at risk * 10^n
What is the point prevalence rate ?
the prevalence rate based on data collected for/at one point in time
What is period prevalence rate?
the number of cases at any time during a specified period
What is lifetime prevalence?
the total number of people known to have had a disease at one point in the life
What are 3 things that can affect prevalence?
- severity of illness
- duration of illness
- the number of new cases
what is the number in the incidence rate formula?
the number of new cases of disease suring a specified time period?
What is the incidence rate formula?
number of new events in a specified time / the population at risk
What is a person-time incidence rate?
a measure or incidence that incorporates times directly into the denominator
