A few days ago my washing machine developed a problem. The phenomena was: The inflow of water would not stop when the power was off. Resulting in flooding.
A service engineer came and inspected the machine. He observed the phenomena. But then he went a step further and created a hypothesis: The water did not stop as the input valve was stuck at open because of sludge(I live in Noida). Then he formulated the corrective action: Chemical wash of the machine to clean out sludge. And that was all that went in his inspection report - no mention of the phenomena.
The workshop people came and collected the machine. The next day they returned a bright-as-new washing machine. But the reported phenomena was still observed! Obviously a chemical wash was not the correct corrective action.
Lesson: Always report the observed phenomena that is to be investigated. Hypotheses should be marked for what they are - reasonable guesses. Most importantly - do not specify a corrective measure without first establishing the defect.
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