Skip to content

Main content

Aliquot Volume Uncertainty Term Tool

Combine equal dispense standard uncertainties under a supplied common correlation; for one dispense correlation has no effect.

Loading tool…

Description

Return equal-uncertainty correlated dispense uncertainty.

Standard uncertainties combine through the measurement model and the covariance of its inputs. Correlated errors may reinforce or cancel, and treating a scale or volume as exact is a substantive assumption. A propagated value is different from a complete uncertainty budget or a statistical decision.

Return equal-uncertainty correlated dispense uncertainty.

When to use this tool

Use Aliquot Volume Uncertainty Term when checking the stated uncertainty-propagation term under supplied correlation and exact-input assumptions.

How to use the tool and how it works

  1. Enter dispenses, perDispenseStandardUncertainty, correlation. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read standardUncertainty. Use the output convention below.

Return equal-uncertainty correlated dispense uncertainty. Require whole dispenses >= 1, per-dispense uncertainty >= 0 and correlation in [-1/(n-1),1] for n>1, otherwise [-1,1]; result = u*sqrt(n*(1+(n-1)*rho)).1

Uncertainty propagation depends on the measurement model and input covariance. Omitting correlations or treating volume as exact requires justification; this helper is only one specified contribution.2

Input fieldMeaning and unitsAccepted input
dispensesDispensesRequired. Safe integer; minimum 1.
perDispenseStandardUncertaintyPer Dispense Standard UncertaintyRequired. Finite number; minimum 0.
correlationCommon pairwise correlation rho, bounded to keep the equal-correlation covariance model nonnegative.Required. Finite number; maximum 1.
Output fieldInterpretationReturned shape
standardUncertaintyStandard UncertaintyRequired. Finite number.
json
{
  "input": {
    "dispenses": 4,
    "perDispenseStandardUncertainty": 0.1,
    "correlation": 0
  },
  "output": {
    "standardUncertainty": 0.2
  }
}

Limitations and assumptions

  • This assumes equal standard uncertainties and equal pairwise correlation; no actual pipette calibration or full uncertainty budget is determined.
  • Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
  • Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Construct a justified measurement model and complete uncertainty budget, including correlations, calibration and omitted scale/volume terms, for reliable uncertainty reporting.

References

  1. Calculation and input contract: biobanking/aliquot-volume-uncertainty-term — tool.io

  2. Guide to the expression of uncertainty in measurement, JCGM 100:2008 — BIPM/JCGM

Similar or alternative tools