Detection capability software for method validation
LoB, LoD, and LoQ estimation per EP17-A2 — parametric and non-parametric approaches, probit regression, and precision profile variance function methods.
Know what your assay can and can't detect
Low-concentration results drive clinical decisions — ruling out disease, screening, monitoring drug levels. If the measurement procedure can't reliably distinguish a true signal from blank noise, you risk reporting false positives or missing genuine low-level results. EP17-A2 defines the framework: limit of blank (LoB) to characterise the noise floor, limit of detection (LoD) to confirm the lowest concentration you can reliably detect, and limit of quantitation (LoQ) to determine where measurement uncertainty is small enough for the result to be clinically useful.
We use Analyse-it frequently for our verification and pre-verification work, in accordance with CLSI guidelines for in-vitro diagnostics. It’s saved time and effort compared to the hodge-podge of applications we used before, JMP, SAS, etc...
Brian Noland, Ph.D.
Principal Scientist, Product Development
Biosite / Inverness Medical Innovations
Analyse-it covers the full EP17-A2 workflow. Parametric and non-parametric LoB from blank material, LoD from pooled SD of low-level samples or from the precision profile variance function, probit regression for molecular and immunoassay methods where detection is probabilistic, and LoQ directly from the variance function. Precision profiles from EP05-A3 feed straight in — no re-entering data, no separate tools.
What's included
Establish or verify the limit of blank
LoB from blank material using parametric (SD) or non-parametric (quantile) approaches, or from the precision profile variance function. Choose the method that matches the distribution of your blank measurements.
Establish or verify the limit of detection
LoD from pooled SD of non-blank materials per EP17-A2, or from the precision profile variance function. Critical for high-sensitivity assays where low-concentration results drive clinical decisions.
Determine LoD for probabilistic detection
Probit regression for assays where detection is not deterministic — increasingly important for molecular and immunoassay methods. LoD at the concentration where detection probability reaches the required threshold.
Determine where measurement uncertainty allows reliable reporting
LoQ from the precision profile variance function, linking to EP05-A3 precision data. The concentration where imprecision falls below the threshold for clinically reliable results.
Example analyses
See detection capability results in detail — LoB, LoD, probit regression, and LoQ — using CLSI example datasets you can download and follow along with.
EP17-A2 — Appendix A
Estradiol detection capability.
Parametric LoB from 5 blank samples and LoD from pooled SD of 5 low-level samples. Frequency density histogram with LoB and LoD lines.
EP17-A2 — Appendix A
Estradiol detection capability, second reagent lot.
Same structure as Example 1 — parametric LoB and LoD with frequency density histogram. Second reagent lot.
EP17-A2 — Appendix B
New Marker, precision profile approach (alternative power).
LoB and LoD estimated from precision profile using 3-parameter alternative power variance function. Six pools across the measuring range.
EP17-A2 — Appendix B
New Marker, precision profile approach (mixed variance).
Same dataset as Example 3, using mixed constant/proportional variance function model.
Validated, reliable, trusted for over 30-years
Validated calculations you can defend at inspection
Every calculation by Analyse-it, no Excel formulas, and no third-party functions. Validated against CLSI reference datasets, published datasets, and thousands of internal test cases. Defensible in a 510(k), CE-IVD technical file, CAP inspection, or ISO 15189 audit. See how we
develop and validate Analyse-it →
Data stays in your facility
Analyse-it runs entirely within Excel on your PC. No cloud processing, no data transmission.
Your pre-submission and patient-adjacent data stays within your facility under your data governance controls.
Standard Excel workbooks
Analyses are ordinary Excel workbooks that you can share with colleagues, archive for audit, and open on any machine with Excel — no Analyse-it licence required.
No formulas to break
Results contain no formulas, so they can’t be accidentally edited or corrupted. The results you reported will be exactly what you find when you reopen the workbook.
Technical details
CLSI protocols
- EP17-A2: Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures
Limit of blank (LoB)
- Parametric (SD of blank material) new in v4.00
- Non-parametric (quantile of blank material) new in v4.00
- From precision profile variance function new in v4.00
Limit of detection (LoD)
- Pooled SD of non-blank materials new in v4.00
- From precision profile variance function new in v4.00
- Probit regression new in v5.50
Limit of quantitation (LoQ)
- From precision profile variance function new in v4.00
Plots
- Frequency density histogram with LoB and LoD
- Probit regression curve new in v5.50
