QAQC Sensitivity Check: The 5-Minute Engineering Review That Catches Hidden Errors

Patrick Law
Aug 11
2 min read

Introduction

In engineering, accuracy isn’t optional — it’s critical. But under tight deadlines, mistakes can slip through, especially in complex calculations or models. The QAQC Sensitivity Check is a rapid, reliable method that can catch hidden formula errors, unit mismatches, and incorrect assumptions in under 5 minutes. It’s a must-have addition to any Level 2 QAQC process.

What is Sensitivity Checking?

Sensitivity checking is the process of altering one key input in your calculation and observing how the output changes. If the output reacts in the expected direction and magnitude, your formula and logic are likely correct. If not, you’ve just caught an error before it reaches the client.

Why It Works

Catches silent errors — Issues like broken cell links or hard-coded values that pass unnoticed in normal reviews.
Verifies logic — Ensures results follow the physical laws or cost relationships they should.
Fast — Takes minutes, not hours, and can be applied to any deliverable.

Example: Pipeline Pressure Drop Calculation

Let’s say you’re calculating the pressure drop in a pipeline. Your key input is flow rate:

Increase the flow rate by 10%.
According to the Darcy–Weisbach relationship, pressure drop should increase by roughly 21%.
If the result matches the expected change — ✅ Pass. If it doesn’t — ❌ Fail and investigate the formula, units, or cell links.

How to Implement in Your QAQC Workflow

Select a key variable that significantly impacts your result.
Adjust it by a small, realistic percentage (±10% is common).
Predict the expected output change based on engineering theory.
Compare predicted vs. actual change.
If they don’t match, dig deeper into the calculation logic.

Pro Tip: AI-Powered Sensitivity Checks

Using AI tools like ChatGPT or Claude, you can automate part of this process. Provide the formula, original inputs, and modified inputs, and let the AI confirm if the result behaves as expected.

Conclusion

The QAQC Sensitivity Check is a lightweight, powerful addition to any engineering review process. It improves accuracy without slowing down deliverables — making it ideal for high-speed, high-quality engineering environments.

Next Steps

For more AI-powered engineering workflows, subscribe to our YouTube channel and check out our course: Singularity AI for Engineers.