The threshold
The sensitivity setting that decides who gets in and who gets refused, left where the installer put it.
The Dial Nobody Turns
Every matching system has a sensitivity setting trading wrong people admitted against right people refused. It is left where the installer put it.
What the Score Distribution Shows
Most readers record a match score for every attempt and show it to nobody. A month of those scores answers the threshold question without changing anything.
One Setting, Two Requirements
The sensitivity that is right for a door is wrong for a clock, and sites run both at the same number because the estate was configured in one afternoon.
Testing It on Your Own People
A pilot that cannot fail is a demonstration. Running one that can takes a week and prevents the most expensive mistake available in this subject.
Spoofing, Proportionately
A fake finger is possible and a photograph on a phone is easier. Whether either is worth defending against on a time clock depends on arithmetic nobody does.
Tuning After a Change
A setting that was right in June is a setting that was right for June. The things it was tuned against — the population, the building, the weather — all move.
Writing the Setting Down
One paragraph converts a configuration default into a decision somebody made, and it is the document that answers the question when it is finally asked.