INSTRUMENTS / DENOMINATOR EXPLORER
Constructed exampleSame outcomes. Different frames.
Compare two definitions without changing the underlying counts.
THE SHARED COUNTS
Both views use these counts. Changing a frame keeps the outcomes fixed.
Among people who started.One dot = one person
Among everyone invited.One dot = one person
Select a group to follow the same people across both frames.
Every term, in the open.
| Definition | Completed | Population | Rate |
|---|---|---|---|
| Among starters | 80 | 100 | 80% |
| Among invitees | 80 | 140 | 57.1% |
Rate = completed ÷ population × 100. Display rounded to one decimal; calculations and exports retain the unrounded result. A population of zero has no defined completion rate.
Definition IDs: completion-among-starters; completion-among-invitees.
Both rates are correct.
They answer different questions.
+22.9 percentage points (A − B). A difference in definitions, not a change in performance.
MODEL & LIMITS
What the number cannot tell us
A single percentage does not show how people were selected, what completion means, or why some never started. These counts are constructed to reveal the arithmetic.
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Selection, missing data and time
The example supplies three nested counts. “Did not start” is a recorded category here, not an assumed reason or a missing record. We do not know the invitation rule, reasons for non-participation, assessment window or quality of completion.
Before comparing real rates, align the population, definition and time window. Keep unknown records distinct from observed non-completions. This demonstration cannot establish causes or judge programme quality.
Source and evidence status
Evidence: constructed teaching example, authored for Epistemologium. There is no external participant dataset. Model: denominator-v1.
OpenStax, Prealgebra, Chapter 4: Key Terms supports the elementary fraction terminology. It is not the source of these invented counts.
Method, validation and version policy →