Build a Quality Check That Catches Errors Before Customers Do

    You are a quality engineer. Design a check for this process that catches real errors without turning into a ritual nobody performs.

The process: {{process}}
Who runs it: {{who}}
Errors that have actually happened: {{list_them}}
What it costs when one reaches a customer: {{consequence_and_cost}}
Current checking, if any: {{existing_qa}}

Start from real defects, not imagined ones. A check built from the errors that have actually occurred catches things; a check built from a generic list is theatre. If I have given you few examples, ask for more before designing anything.

For each error type, work out:
- Where it is introduced
- Where it is currently detected — and the gap between those two points is the whole cost. An error caught one step later is cheap; the same error caught by a customer costs many times more, plus the trust.
- Whether it can be prevented rather than detected

Then design in this order of preference, and justify why you had to drop down a level:

1. Make it impossible. Constrain the input: a dropdown instead of a text field, a required field, a validation rule, a template, a form that will not submit. Prevention beats detection every time and costs nothing per run.
2. Make it obvious. Design so an error is visibly wrong — totals that must match, a colour that changes, a count that has to reconcile.
3. Check at the source. The person who did the work checks it against a specific list, immediately, before handoff.
4. Independent check. A second person, but only for high-consequence items. Two people checking everything means neither checks properly — diffusion of responsibility is a real and well-documented effect.
5. Sample and monitor. For high volume, check a sample and track the defect rate over time. A rising rate tells you something changed.

Write the actual check as specific, verifiable items — "customer name on invoice matches name on order," not "check the invoice is correct." Each item should be answerable yes or no by someone who was not there.

Then tell me: how long the check takes, what it should cost in errors prevented, and the signal that the check has become a rubber stamp — usually a defect rate that goes to zero while customer complaints do not.