The fact must be expressed as data, but there is a problem in that the correct data is difficult to catch. So that I always say "When you see the data, doubt it!" "When you see the measurement instrument, doubt it!... For example, if the methods such as sampling, measurement, testing and chemical analysis methods were incorrect, data... to measure true characteristics and in an unavoidable case, using statistical sensory test and express them as data.

Kaoru Ishikawa in: Annual Quality Congress Transactions, (1981), p. 130