Eligible universe
Also known as: Target population · Eligible base · Sampling frame · Contract universe
The full set of cases that qualify for a test — the population the sample is drawn from — defined by explicit cutoff, deduplication and date rules before any draw.
Legal basis
Wikipedia — Sampling frame
Before drawing, you have to say where you are drawing from. The eligible universe is that set: every contract or person that meets the test's rules — for example, a start date up to a certain cutoff, one row per person (keeping the oldest record when the same tax ID appears more than once), cancellations included or not. It is what statistics calls the sampling frame.
Defining the universe clearly is what lets you reweight later: the totals of the eligible population — how many cases exist and how many had the event — are the numbers that give the sample back its real proportions. A poorly defined universe contaminates everything that follows, because the sample ends up representing a population nobody can name.
Frequently asked questions
What is the eligible universe of a test?
It is the full population of cases that qualify for the test, defined by explicit rules (cutoff date, one row per person, inclusion of cancellations and so on) before the draw. It is the sampling frame the sample is drawn from, and whose totals make reweighting possible.