Event-time risk-set control sampling

Sample eligible controls at events

At each incident event, eligible controls are members of the cohort still at risk. Repeated control selection and later case status are allowed by incidence-density sampling. Unique-person counts and sampling appearances must not be added as disjoint groups.

Flow diagram

Steps

Identify incident cases

Specify event definition and ascertainment in the source cohort.

Construct each event-time risk set

Include only cohort members eligible and at risk at that event time.

Apply matching rules

Define matching variables, calipers and eligible control counts.

Sample controls reproducibly

State replacement, reuse across risk sets and random sampling procedures.

Retain matched-set membership

Record event time, case/control role and sampling probabilities as applicable.

Incident cases

Record people using the documented inclusion definition. This count is not a disjoint partition of the other count nodes.

Sampled control appearances

Record control appearances using the documented inclusion definition. This count is not a disjoint partition of the other count nodes.