Earlier quoted context omitted.
If you don't know exactly what you are measuring, the measurement is worthless. We must therefore isolate the measurement subject for the measurement, and avoid uncontrollable influences as far as possible. This is how engineering works, and every engineer should also be aware of measurement errors. In addition, repeatability and falsifiability of the experiment and conclusions are required for scientific claims. The…
Their point seems to be a tautology: If what you are measuring is worthless, the measurement is worthless. Whether the measurement is in-some-sense formally correct or not is another question.
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