17 Questions
What assumptions are made when calculating risk (incidence proportion) and incidence odds?
Closed population without competing risks
Which term is used to describe the frequency of new disease events or outcomes occurring in a given follow-up period?
Incidence Rate
What does person-time at risk refer to in data analysis?
The total time of follow-up for all persons in the study population
Which of the following is another name for incidence density?
Outcome Density
What happens to the risk assumptions with longer periods of follow-up in cohort studies?
They tend to be violated
What is the definition of risk or incidence proportion?
The proportion of persons at risk in a population who develop the disease or outcome during a specific time period
What does risk range from in terms of values?
0 to 1
What does risk represent in terms of probability?
The average probability that a person in the population will develop the disease or outcome over a given period of time
In what unit is risk measured?
Dimensionless (no units)
What is the calculation for incidence proportion if A represents the number of new cases of disease or outcomes during ∆t and N0 represents the number of persons at risk at the start of the time period?
(A / N0)
What does it mean when risk is a function of events over time?
The risk can increase or decrease as events unfold over a period of time
What is the Risk Difference (RD) in the first practice problem?
0.15
In the first practice problem, what does a Risk Ratio (RR) of 2.0 indicate?
The one-year risk among the exposed is 2 times the one-year risk among the unexposed.
What does an Incidence Rate Difference (IRD) of 0 indicate?
No difference in incidence rates between exposed and unexposed individuals.
What range does the Incidence Rate Ratio (IRR) cover?
0 to ∞
How is the Risk Difference (RD) interpreted in practice problem #4?
Difference in risk between exposed and unexposed groups.
What is the interpretation of the Risk Ratio (RR) in practice problem #4?
Risk among exposed is 2 times risk among unexposed.
Learn about calculating risk (or incidence proportion) and understanding how it varies based on the specified time period. Explore the concept of the proportion of persons at risk in a population who develop a disease or outcome within a specific time frame.
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