# How assays are stored

> Sample → assay → certificate → method → lab: how lab results are stored and why.

Source: https://geodb.io/guide/topic/assay_data_model/ · Category: Understanding your data
Lab results in geoDB are **normalized** — every measured value is stored
once, with its full lab context, instead of as a flat spreadsheet. It's the
single most important idea in the data model, and the reason QC checks,
method comparisons and clean exports work later without hand-editing.

## The chain, one link at a time

- A **sample** is the physical material — a drill interval sample or a
  surface point sample — that you sent to the lab.
- An **assay** is that sample's appearance on one lab job: it links the
  sample to a **certificate**.
- A **certificate** is the lab job itself — everything the lab returned
  together, and a record of which analytical methods were used.
- Each measured value is an **assay unit**: one element, one value, one
  unit — measured by exactly one **method**.
- A **method** (Au-AA24, ME-ICP61, a lab's own code) belongs to a
  **laboratory** and carries its detection limits.

The spreadsheet the lab emailed you is a *presentation* of this chain —
one row per sample, one column per element. geoDB unpacks it into the
chain on import and can re-flatten it any time you export.

## Why bother? Three payoffs

**The same element, analysed two ways, never collides.** A fire-assay gold
value and an ICP gold value live side by side — each tied to its own
method. Your project's **merge settings** decide which method wins when a
single number is needed: on exports, strip logs, and the 3D display. You
can change that preference any time without touching the stored data.

**"Less than detection" is never a fake zero.** Below-detection results
are stored as a −1 marker plus the method's detection limit. Averages,
statistics and exports can treat them properly — a real 0.00 and a
"below 0.005" are different facts, and geoDB keeps them different.

**QC rides for free.** Standards, blanks and duplicates go through the
same chain as ordinary samples, so every certificate can be judged — did
the standards read back their certified values? were the blanks clean? —
without any re-keying. That judging happens on the QC pages, covered in
the next topic.

## Where you see the pieces

Certificates, methods and labs each have their own pages under your
project's data section — useful when a lab renames a method mid-program or
a certificate needs its paperwork checked. Day to day you'll mostly meet
assays already flattened: on sample tables, strip logs, and exports.