Each module’s values, confidence intervals and pass/fail decisions are checked against independently worked answers, published worked examples or both. These checks are evidence about the calculations. Your laboratory supplies its own study evidence and makes its own decision.
Every calculation shows its method and published sources under Methods and sources on the Results stage. See Methods and sources.
Validation by module#
Descriptive summary#
Checked against the NIST mean, sample SD and Student t interval formulas, calculated independently.
Inputs 2, 4, 6, 8 and 10 give mean 6, sample variance 10 and SD √10. Intervals are checked at 90%, 95% and 99% confidence. The checks also cover 0,125 typed in a decimal-point study, which would otherwise read as 125.
Repeatability#
Checked against the NIST sample SD, CV and Student t mean-interval formulas.
A 20-result example gives mean 100.17, SD 0.936 and CV 0.935%. The mean limit is met, a CV limit of 0.8% is not, and the excluded result stays out of the calculation.
Multi-day precision#
Checked against independent nested variance-component calculations and the Chakravarthy 2019 and LabMed precision datasets.
The checks cover repeatability, between-run and between-day components, and within-laboratory SD and CV, including components estimated at zero.
Bias against an assigned value#
Checked against independent bias, recovery and combined-uncertainty calculations and the NIST Student t formulas.
Results 2, 4, 6, 8 and 10 against an assigned value of 5 give bias +1, percent bias +20% and recovery 120%.
Correcting an assigned value from 100 to 110 makes a limit set on 100 read Undecided until you review it. For mean 100, the corrected 8%-or-6-unit allowance is 8.8 units, and a difference of 10 fails.
Method comparison#
Checked against the Giavarina 2015 worked example and independent OLS, Deming, weighted Deming and Passing–Bablok calculations. Weighted Deming is checked against values based on the Linnet method in R’s mcr package.
Specimen acceptance is checked by exact counting. Twenty differences alternating −10 and +10 have mean 0 but none within ±5, so the limit is not met. With the greater of 6 mg/dL or 8%, comparative results 50, 75, 100, 200 and 300 get limits 6, 6, 8, 16 and 24. A difference exactly on a limit passes. Specimens with missing results are counted the same way under the comparison and lot rules.
Instrument comparison#
Checked against independent paired-difference calculations and the NIST Student t formulas.
Differences 4, 5 and 6 give mean bias 5 and SD 1. The checks also cover changing the reference instrument, replicate averaging, missing results and limit boundaries. The specimen limit uses the same counts as method comparison.
Reagent lot comparison#
Checked against exact specimen differences and concentration-dependent allowable error, with replicates averaged for each specimen.
At previous-lot result 100 and a 10% limit, new result 89.9 fails (−10.1%), and results 90 and 110 pass at the limits. With the greater of 6 units or 8%, previous results 50, 75, 100 and 200 get limits 6, 6, 8 and 16. Missing pairs, uncovered limits and incomplete plans can't pass.
Supporting mean differences, intervals and imprecision are checked with independent Student t and chi-square calculations.
Linearity#
Checked against independent least-squares calculations and the Xiao and Chambliss 2023 LDH dataset.
Slope, intercept, deviations and recovery match separately solved normal equations. Three levels prepared at only two distinct concentrations can't be calculated.
Dilution verification#
Checked against independently calculated dilution factors, corrected concentrations and recovery decisions.
Volumes of 100 + 400 give factor 5, and a measured 100 gives corrected concentration 500 and recovery 100%. Serial factors 5 × 2 give factor 10. The checks also cover mismatched factors, results outside the measuring interval and range endpoints.
Reference interval verification#
Checked by independent counting of subject results and exact calculation of staged decision rules.
Against limits 70–100, results 69.9, 70, 85, 100 and 100.1 give 1 below, 3 within and 1 above. The checks also cover repeat subjects, separate partitions, one-sided limits and staged decisions.
Reference interval establishment#
Checked against independent Hyndman–Fan type-6 quantile and binomial-rank calculations, normal-theory examples and R calculations of log-normal intervals.
The checks cover one-sided and two-sided reference limits and their confidence intervals. Log-normal limits are compared with R at 90%, 95% and 99% confidence.
Qualitative agreement#
Checked against the FDA 2007 diagnostic-test guidance and independent agreement, Wilson-interval, kappa and McNemar calculations. Further interval checks use Fleiss–Cohen–Everitt and Newcombe examples and R. A nonreportable first result keeps an agreement limit from passing.
Near-cutoff precision#
Checked against independent Wilson intervals, probit fits and Fieller confidence limits.
A separate Fisher-scoring calculation gives the expected C5, C50 and C95. The checks cover hit-rate counts, confidence limits, failed fits and concentrations outside the measured range. A nonreportable replicate keeps a fitted-cutoff limit from passing.
Detection limits#
Checked against independent Armbruster and Pry 2008 LoB and LoD calculations, percentile calculations and LoQ examples.
LoB checks cover normal-theory and type-7 percentile estimates with independent binomial-rank intervals. LoD checks recalculate the pooled low-level SD and LoB + z × SD. LoQ checks confirm the lowest tested concentration that meets the quantitation goal, and the resulting decision.
Carryover#
Checked against the pSMILE 21-position calculation, with independently derived low-after-low SD, low-after-high means and decisions.
The checks cover all 21 positions, the signed mean difference and the rule that carryover must be below the error limit. The historical high-then-low design has separate Broughton and Haeckel arithmetic checks.
Interference#
Checked against independent test-minus-control differences and the NIST Welch–Satterthwaite interval formulas.
The checks cover matched controls, absolute and percentage limits, intervals crossing a limit and missing controls. A test aliquot without a matched control stays in the result as undecided.
Stability#
Checked against independent paired-change and NIST Welch–Satterthwaite calculations, with separately derived Student t limits.
The checks cover paired and independent designs, a baseline for each condition, material counts, absolute and percentage changes, and the supported duration.
Sigma metric#
Checked against independent examples of the Westgard, Bayat and Westgard 2019 sigma formula, Equation 5.
At concentration 100, TEa 6, absolute bias 1.5 and SD 0.9 give sigma 5. The checks also cover absolute and percentage inputs, unit conversions and zero imprecision.
QC targets (ADM export)#
Checked against independent decimal-arithmetic examples using the sample SD and CV definitions.
Results 139.0, 140.0 and 141.0 give mean 140, sample SD 1 and CV 5/7%. The checks cover grouping by instrument, lot, analyte and level, decimal rounding, baseline dates, exclusions and nonnumeric results.
Workflow checks#
Import, calculation, correction, reopening, sign-off and the report of every study type are checked from start to finish with made-up data. The values, counts, units, intervals and outcomes in each PDF are compared with the saved result, and sign-off changes no outcome.
Traceability#
Each check has fixed inputs, independently worked expected values and stated tolerances. A calculation change gets a new Method ID, recorded with every saved result. See Methods and sources and History and revisions.