Intro Flashcards
Fixed vs Dyanmic population?
Fixed - permanent membership defined by an event
Dynamic - membership transient by being in/out of a state
Proportion vs ratio
proportion is how much of a pool meets a criteria. ratio is one pool vs a different pool
Incidence is defined as?
new cases of a disease that occur in a period of time divided by # people at risk for that disease during the time
Does “at risk” include those who already have the disease or can’t get it?
lol no
Person time is what?
amount of time a person is at risk up until they die, get diseased, or lost to care
Cumulative incidence is what?
a proportion of a population who gets the disease per time (for ex. one-year incidence of HIV in blood transfusion patients is 3%)
Incidence rate vs cumulative incidence?
Incidence rate is a rate (new cases / observation time) while cumulative incidence is a proportion of (new cases in specified period/people at risk)
Incidence is in terms of cases per year, while cumulative is chance of getting.
Prevalence is?
affected persons/# people in a population
Prevalence useful for determining cause? Tells us what?
No; tells us how much but not why
What is point prevalence?
proportion of population that has disease at a point in time (either calendar time or a life event like birth)
What is period prevalence?
prevalence over a period
Prevalence vs incidence?
Prevalence is chance of having the disease at a point in time.
Incidence is chance of developing the disease at a point in time.
Prevalence = incidence rate x duration
Cumulative incidence vs Incidence Rate
CI less accurate, useful for fixed populations
IR more accurate, useful for dynamic populations
Mortality rate? All-cause mortality rate?
Mortality rate: deaths from a disease / total population
All-cause: deaths from a disease/all deaths
case fatality rate is?
proportion of people who die that had disease
