If you are making a decision based upon a measurement, then you have two choices.
One, you can simply accept any number a machine produces as true; or
Two, you can ask “how did you get that number?”
The choice you make should be based upon how important the decision is that you’re basing the measurement upon. If you just want to know how hot it is outside, a twenty-year-old thermometer, combined with stepping outside will probably do. However, if the measurement is critical to an important outcome, then you need to ask, and answer, the question how did you get the number?
A critical measurement is a measurement where, the result of an important analysis, is dependent upon the measurement. A measurement is critical if an incorrect measurement could place people in danger. If a scientist measured the wrong amount of a drug when making a pill, then it could harm someone – that is a critical measurement.
If a lab employee measures the wrong amount of alcohol in your system in a DUI case, then it could result in an unwarranted prison sentence – that is also a critical measurement.