Student guide

This guide is for students learning assay quality control with QC Analytical Results.

This guide is for students learning assay quality control with QC Analytical Results. The help pages earlier in this manual say where each control is. This guide says what each control does to your data, what you will see, and why you would use it. It covers the working tabs in depth:

Words in bold are the labels you see on screen. The Glossary explains terms such as CRM, relative difference and check stage.

How the app is put together

The app works on QC results. These are the extra samples a project sends to the laboratory with its real samples, to check the laboratory’s work.

QC type The sample What it tests The question
Precision A duplicate, the same material split in two and assayed twice. Repeatability. Does the lab get the same answer twice?
Accuracy A certified reference material (CRM), a sample with a certified true value. Bias. Does the lab get the right answer?
Contamination A blank, a sample with none of the element in it. Carry-over between samples. Does the lab find metal where there is none?

Each result arrives in a despatch, a batch of samples sent to the laboratory and returned together. Most of the app’s checks look at results despatch by despatch, in date order. That is how a laboratory problem shows itself. It starts in one despatch and continues in the next.

The app has four working parts:

  1. The data source at the top right decides where the results come from. Demo loads the bundled demo data, Upload reads your own Excel or CSV export laid out as the templates, and Projects opens a project saved to your account once you are signed in. Nothing changes your file, and an upload is kept only if you choose Save afterwards, which adds it to a project.
  2. The Filters in the band under the tabs choose which results the Charts, Data and Statistics tabs use. They set the QC type, laboratory, analysis suite, analyte, check stage or CRM, and the dates or despatches.
  3. The Overview ignores the Filters. It checks every laboratory, analyte and date in the data at once, against rules you can see and change. It sums up each laboratory as a Lab Confidence of High, Moderate or Low.
  4. The Charts, Data and Statistics tabs draw, list and measure the results the Filters pick out. Every finding on the Overview has a button that opens the chart behind it, with the Filters already set.

The app redraws the charts and tables as soon as you change a filter or a chart setting, and the Overview as soon as you apply a rule. It remembers only two things between visits. Your Overview rules are saved with your account when you are signed in, so they follow you to any computer, and otherwise in your browser. Your chart settings are saved in your browser.

A first session (about 30 minutes)

Before you start. This first session uses the demo data, which needs no account. Open QC Analytical Results at qaqc.app.geoscience-analytics.com and begin. To use your own data later, you need a Geoscience Analytics Toolkit account. At toolkit.app.geoscience-analytics.com click Create an account, choose Student under You are, and confirm your email with the 6-digit code we send you.

We check each new account before switching it on, usually within a day, and email you when it is ready. One account opens every app in the Toolkit and keeps the Overview rules you save.

Work through this with the demo data before using your own. The demo is three years of realistic QC from two laboratories, up to November 2025. It holds 46,104 duplicate results and 39,919 CRM and blank results.

  1. Start on the Overview. The app opens there, on ALS, the laboratory with the newest data. Read the top line, Lab Confidence: Low, and the headline under it: Mo_MEICP41s_ppm: sustained negative CRM bias of −1.4 SD since despatch 17301 (16/09/2024). That one sentence is the laboratory’s most serious finding.
  2. Read the four domain cards. Accuracy (CRMs) is Fail, with 9 analytes biased and 19 to watch, of 37. Precision (duplicates) is Warn, with none over the action limit and 7 to watch, of 171 analytes and stages. Contamination (blanks) is Fail, with 7 analytes contaminated in the latest despatch. Despatch coverage is Fail, because there are no duplicate results from Feb 2024 to Jun 2024. The Key Takeaway puts these in order of importance.
  3. Open the Rules. Click Rules at the top of Lab Health. Every number behind the verdicts is here. CRM bias fails from ±1 SD, pulp duplicates are allowed ±10% relative difference, and a blank fails when it is more than 5× the detection limit above its certified value. Close the window with Cancel, and nothing changes. The Overview guide goes through each rule.
  4. Follow a finding to its chart. In Current Risks, the first row is Mo_MEICP41s_ppm: the latest EXP-3 result is 9.0 SD below certified. Click Investigate. The app sets the Filters to Accuracy, ALS, Mo_MEICP41s_ppm and CRM EXP-3, and opens a Shewhart chart. A note above the chart says where you came from. The results sit well below the certified value of 3.8, because the lab has reported this CRM low for a year.
  5. Change the chart. In the Charting menu on the left, set Chart to Cusum. The line falls steadily, because a cumulative sum drifts when every result is on one side of the target. This is the chart the Overview used to find the bias. Open How this is calculated under the chart title to see the formula with this chart’s own numbers.
  6. Look at duplicates. In the Filters, set QC type to Precision, Sample check stage to Pulverising Stage and Analyte to Cu_MEICP41s_ppm. The Scatter chart plots Sample 1 of each pair against Sample 2, and good pairs sit on the X = Y line. Change Chart to RD v Mean Pairs. Each pair is now one point, its relative difference against its concentration, and pairs beyond the 3 SD line are outliers.
  7. Switch to the laboratory with less data. Back on the Overview, click SGS. It has duplicates only, so Accuracy and Contamination show N/A. Lab Confidence is still Low, and the headline says why: No CRM or blank results from Jan 2025 to Jun 2025. The coverage check fails because six months of despatches have no QC of that kind at all. Missing QC is a finding too.
  8. Check the file itself. Open the Data tab and look at the Data health bar at the top. It reads Demo data · 46,104 rows · 1 warning. The warning is 25 rows with no detection limit, and reads 25 rows have a blank in a key column (for example LOWERDETECTION). Results below detection aren’t listed, because they are always left out. The Data guide lists every check, and each finding says what is odd, why it matters and what to check.

By the end you will have seen the three QC types, how the app reaches a verdict from rules you can read, and how each finding leads to its chart and rows.

Good habits

  • Start on the Overview, not the charts. With 100 analytes, four check stages and two laboratories there are thousands of charts. The Overview has already looked at all of them and ranked what matters.
  • Read the rule before you trust the verdict. A Fail is only as good as the limit behind it. Open Rules, check that a 10% pulp limit or a ±1 SD bias limit suits your project and element, and change it if it doesn’t.
  • Mind the threshold. Relative differences blow up near the detection limit, where 0.1 against 0.2 is a 67% difference that means nothing. The Overview counts only pairs with a mean of at least 10× the detection limit. On the charts you set the Threshold factor yourself, and it starts at 0.
  • One suite, one stage at a time. Results from different methods or sample stages have different precision, and mixing them hides the poor one. That is why the Filters start on one suite and one stage. Choose All Suites only when you mean to pool them.
  • Check Data health first with your own file. A result typed as text, an unreadable date or a CRM with no certified SD can quietly remove results from every chart. The Data tab tells you what it found and shows the rows.
  • Report the settings with the result. The RD formula, the threshold, the control-line method and the date range all change what a chart shows. How this is calculated lists them for the chart you are looking at.

When the app changes

The app is still being developed. We check this guide against the app each time we rebuild the manual, and What’s new lists the changes. If the screen and this guide disagree, the screen is right. Tell us through the Feedback tab.