Method Validation Edition

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. Getting detection limits wrong means either under-reporting (clinically dangerous) or over-reporting (eroding trust in the assay). EP17-A2 defines the framework: LoB characterises the noise floor, LoD confirms the lowest concentration you can reliably detect, and LoQ determines where measurement uncertainty is small enough for the result to be clinically actionable.

Analyse-it covers the full EP17-A2 workflow with multiple estimation approaches for each limit. Precision profiles from EP05-A3 studies feed directly into the variance function methods — no re-entering data, no separate tools for LoB, LoD, and LoQ.

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

What's included

Limit of blank from blank material or precision profile

Parametric LoB from the SD of blank measurements, non-parametric from the quantile, or from the precision profile variance function when an EP05-A3 study is already available. Frequency density histogram with LoB and LoD lines overlaid.

Limit of detection from low-level samples or probit regression

LoD from pooled SD of non-blank materials per EP17-A2, from the precision profile variance function, or via probit regression for molecular and immunoassay methods where detection is probabilistic. Probit determines the LoD at the concentration where detection probability reaches the required threshold — such as 95%.

Limit of quantitation from precision profile

LoQ directly from the precision profile variance function, linking EP17-A2 to EP05-A3 precision data — the concentration where imprecision drops below the threshold for clinically reliable quantitative results, such as a CV of 10% or 20%.

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.

Part of measurement system analysis

Detection capability is one part of measurement system analysis, alongside precision (EP05-A3), linearity (EP06-A), bias/trueness verification (EP15-A3), and interference evaluation (EP10-A3-AMD). Precision profiles from EP05-A3 feed directly into detection capability estimation.

See the full MSA workflow on the measurement system analysis page →

Software you can trust

Validated calculations you can defend at inspection Every calculation is performed by Analyse-it — no Excel formulas, no third-party functions. Results are validated against CLSI reference datasets, published datasets, and thousands of internal test cases before every release. See how we develop and validate Analyse-it →

Data stays in your facility Analyse-it runs entirely within Microsoft Excel on your PC. No cloud processing, no data transmission. Pre-submission data, patient-adjacent data, and in-process results stay within your facility under your own data governance controls.

Standard Excel workbooks anyone can open Every analysis is an ordinary .xlsx workbook. Share with colleagues, submit to regulatory affairs, archive for audit, open on any PC with Excel. No proprietary format, no licence required to view results. Colleagues and auditors see exactly what you see.

Results that can’t be accidentally broken Analysis output contains computed values, not formulas. Nothing to accidentally overwrite, no cell references to break, no formula errors to introduce. The results you reported are exactly what you’ll find when you reopen the workbook months or years later for an audit.

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

Method Validation Edition 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.