# The QC system — trusting your numbers

> Standards, blanks and duplicates — and the verdict pages that judge every certificate.

Source: https://geodb.io/guide/topic/qc_system/ · Category: Understanding your data
Quality control is how you *earn* the right to use your assay numbers — in
a resource estimate, a press release, or just a drill-hole decision. The
idea is old and simple: slip known quantities in among your samples, and
check what the lab says about them.

## The three checks

- **Standards** — pulps with certified element values. If the lab reports
  a standard well outside its certified range, every number on that
  certificate deserves suspicion.
- **Blanks** — barren material. Any real grade in a blank means
  contamination or sample-swap somewhere between the splitter and the
  instrument.
- **Duplicates** — splits of the same material submitted twice. They
  measure repeatability; wildly different pairs point at nugget effect or
  lab precision problems.

The lab never knows which samples are the tests — that's the whole point.

## Where verdicts live: the QC pages

geoDB judges these automatically, **certificate by certificate**, on your
project's **QC pages** — charts of standard performance against certified
limits, blank results over time, duplicate scatter, and a verdict per
certificate. When something fails, the failure is visible and attributable:
*this* certificate, *this* standard, *this* much out.

One habit worth building: **the QC pages are the one place QC verdicts
come from.** Ad-hoc checks in a spreadsheet — or a quick statistical look
you ask Petra for — are fine for exploring, but the verdict of record is
the QC page, and Petra will point you there rather than re-derive one.

## Getting QC data in

Nothing extra to do on the way *in*: QC samples arrive with your ordinary
imports. When a certificate lands, geoDB recognises standards, blanks and
duplicates (from your sample naming and the reference-standards library),
attaches them to the certificate, and the verdict pages update. Your
project can pre-select which certified reference materials it uses, so
loggers pick from a short list instead of the whole catalogue.

How often QC samples *go in* — every N samples, and which types — is set
separately, in a **[QC insertion protocol](https://geodb.io/guide/topic/qc_protocols/)**. A
project can hold several (an RC campaign and a soils grid want different
rates), with one marked as the default.