A percentage that answers the wrong question

An EDTA peripheral-blood leukocyte preparation has 50,000 acquired events. An initial analysis calls 2,286 CD19-positive events 4.6% because it divides by all acquired events. The calculation is correct, but the statement hides the population that was actually analyzed. The question is how the cytometer made those events and how the gate tree defines the result.

The preparation was stained with a viability dye, CD45, CD3, and CD19. Conventional compensation was calculated from matched single-color controls before review. The time plot was stable, and an unstained control showed modest background.

The release-ready teaching wording is CD19-positive events: 19.0% of viable, singlet, CD45-bright lymphocyte events, 2,286 of 12,038. That denominator makes the path to the population visible. It does not establish normality, clonality, or a diagnosis. State the parent gate whenever a gated percentage is communicated.