TEa · APS · Sigma · MU Calculator v5 (replica)

TEa, APS, Sigma & Measurement of Uncertainty Calculator

Search clinical analytes with EFLM meta-analysis BV data. Enter your verification CV% and Bias%, configure uncertainty sources (calibrator, reference method), and calculate TEa, APS, Sigma, and expanded MU.

How to use this calculator

1Analyte & BV Data

Search by analyte name, synonym, or abbreviation (e.g. HbA1c, ALT, creatinine). Select from the dropdown to auto-fill CVI and CVG.

2Verification Results

CV% — Within-lab reproducibility from a minimum 20-day precision study (EP05 / ISO 5725-2). Use total CV.

Bias% — Systematic difference from a reference method or peer-group comparison (EP09 / CLSI C53 / EQA bias). The calculator uses |Bias| internally.

3MU Options

k = 2 for ~95% coverage (routine). k = 3 for ~99.7% (high-stakes). U_cal% from the calibrator/SRM certificate, divided by k_cal to get u_cal.

Override CVI / CVG when:

Your lab uses an in-house or RCPA biological variation estimate.
The analyte matrix differs (e.g. whole blood vs serum).
CVG is absent — APS bias and TEa will show N/A.

What the results show

TEa — observed total error: |Bias| + 1.65 × CV.
APS table — pass/fail at Optimal, Desirable & Minimum levels (Ricos / Fraser).
Sigma (σ) — σ = (TEa_APS − |Bias|) / CV vs Desirable APS, with gauge.
MU card — U = k × √(u²_imp + u²_bias + u²_cal), with variance budget.
OPSpecs — observed operating point on a normalised σ-band chart.

Analyte & BV Data

Median CVI / CVG from published BV meta-analyses

Analyte 85 common analytes seeded from published BV literature. Verify against current EFLM database for clinical use.

CVI % Within-individual biological variation · editable

CVG % optional Between-individual biological variation · required for APS bias and TEa

Verification Results

From precision and trueness studies

Observed Imprecision CV% From your precision study (within-lab / intermediate)

Observed Bias% From trueness / bias study · signed or absolute

Measurement Uncertainty Options

ISO 15189 / EA-4/16

Coverage factor k

k = 2 (~95%) k = 3 (~99.7%) Custom

Reference concentration optional Converts relative U% to absolute units (e.g. mmol/L) at a clinically relevant decision point.

Calibrator expanded uncertainty U_cal % optional From calibrator / SRM certificate · JCTLM-traceable

Calibrator k_cal Coverage factor on certificate (usually 2)

Verification report

—

Observed TEa—
|Bias| + 1.65 × CV

Sigma · Desirable APS

—

Highest APS level passed

—

U (expanded MU)

—

k × √(u²imp + u²bias + u²cal)

APS Performance Table

Ricos / Fraser model

Level	TEa allowable	Observed TEa	% used	Status

U — ISO 15189 / EA-4/16 / EURACHEM CG4

u_imp · imprecision

—

= CV_obs

u_bias · trueness

—

= |Bias| / √3

u_cal · calibrator

—

= U_cal / k_cal

u_c · combined

—

= √(u²_imp + u²_bias + u²_cal)

U (expanded): — k: — vs APS desirable TEa: —

Variance budget — contribution to u²c

Imprecision — Bias — Calibrator —

Normalised OPSpecs Chart

Allowable Bias vs Allowable CV

Observed operating point APS allowable limits (◆) Sigma quality lines

X = CV_obs / TEa_des × 100% · Y = |Bias_obs| / TEa_des × 100% · σ = (TEa − |Bias|) / CV

Session history

Analyte	CV%	Bias%	σ Desirable	Highest APS	U (k=2)	When