Setting Up the Experiment

Both the reference method (X) and test method (Y) must be configured separately. For each method:

• Method name — A descriptive label for the analyzer or reagent system (e.g., instrument model, reagent brand)
• ISI — The International Sensitivity Index from the reagent lot's package insert. Must be entered for each method independently, as each lot has its own ISI.
• Normal Patient Mean (NPM) — The PT geometric mean established via the Geometric Mean & VRI module for the specific reagent lot in use on this method. The NPM is the denominator in the INR formula and must be current and lot-specific.
• Operator, reagent lot, calibrator — Optional fields for traceability documentation. Do not affect calculations.

PT and INR are configured independently for pass/fail criteria:

• Total Allowable Error (TEa) — The maximum acceptable total error for PT and INR. TEa should be sourced from your laboratory's established performance specifications, CLIA proficiency testing criteria, or biological variation goals.
• Bias Allocation (%) — The portion of TEa allocated to systematic error (bias) specifically. The allowable systematic error bounds shown on the Bland-Altman plots are derived as: TEa × Bias Allocation%.
• Confidence Level — The statistical confidence level for regression confidence intervals (typically 95%).

If MDPs are included, configure the following:

• Regression type — Deming (recommended), OLS, or Passing-Bablok. This selection determines which regression coefficients are used for MDP bias estimation.
• PT MDPs (1–5) — Clinically important PT values expressed in seconds as reference method (X) concentrations. Common choices: the upper limit of normal PT, and values in the therapeutic anticoagulation range.
• INR MDPs (1–5) — Clinically important INR values as reference method (X) concentrations. Common choices: 2.0 (therapeutic target lower bound), 2.5 (mid-therapeutic), 3.0 (therapeutic upper bound), and 4.0–5.0 (supratherapeutic alert threshold).

For each patient sample, enter:

INR values for both methods are computed automatically from the PT values using each method's configured ISI and NPM — you do not need to enter INR values manually.