Statistics and risk
Incidence
The number of new cases occurring in a population over time.
What it means
Definition
Incidence: Incidence describes new cases, usually over a defined period. It is different from prevalence, which counts existing cases.
What it can tell you
It can help clarify what sort of evidence or claim is being discussed.
What it cannot tell you
It cannot, by itself, prove that the headline is accurate or clinically important.
Headline trap
Why this matters in headlines
A study on new dementia diagnoses is reporting incidence, not the total number of people living with dementia.