CFCM / TOOLS / EDUCATIONAL PROTOTYPE
Laboratory calculation bench.
Understand the arithmetic. Keep the interpretation separate.
Two transparent teaching calculators. No patient identifiers, specimen files or clinical decisions. The calculator code performs arithmetic in the browser and does not send or store its inputs.
The interactive calculators require JavaScript. The worked examples and formulas below remain available without it.
Worked examples, without hidden rules.
Event fraction
15 target events among 750,000 eligible events gives 100 × 15 / 750,000 = 0.002%, or 20 per million eligible events. The ideal Poisson counting CV is 100 / √15 ≈ 25.8%. These are synthetic numbers, not a clinical MRD result.
Dilution
With a stock concentration of 10 units/mL, a target of 2 units/mL and a final volume of 1,000 µL, the stock volume is 1,000 × 2 / 10 = 200 µL. Under the additive-volume assumption, the diluent volume is 800 µL. Concentration units must match; both volumes use the selected volume unit.
Scope of the calculations
The Poisson formula describes an ideal counting model, not total assay performance. Detection and quantification require their own evidence. The dilution relation assumes the solute amount is conserved; it does not establish an appropriate staining condition or handling procedure.
NIST: Poisson distribution · CLSI EP17: detection-capability scope
Prototype 0.1.3 · Local calculation and reset controls updated; formulas and output formatting are unchanged from version 0.1.2. The ideal Poisson counting CV is displayed to two decimal places; other outputs use six significant digits. Display rounding is not a precision claim. Use synthetic values to explore the formulas. No pass/fail clinical classification is generated.
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