What makes people fail a Lean Six Sigma exam

It is the first mechanism, and by far the most frequent. A candidate knows perfectly well what an Ishikawa diagram is, what a SIPOC is and what a control chart is. Faced with a situation, they do not know which of the three applies.

Exams exploit exactly that gap: a good share of the questions describe a context and ask which tool is suitable, or which phase of the approach one is in. Revising tool by tool, without ever placing them back in the order of the process, does not prepare for those questions.

The remedy is simple to state: for each tool, be able to say at which phase it serves, what it requires as input and what it produces as output. A tool you cannot place in the sequence is a tool you will not be able to choose.

Exam questions are written to discriminate, so they contain words that change everything: "most", "first", "except", "before". A right answer to a different question from the one asked is a wrong answer, and it is an entirely avoidable cause of failure.

The most common case is that of questions with several plausible answers. Two options are correct in themselves, but only one answers what is asked — the most complete, the first in order, or the one that applies to the context described. The candidate who has recognised a right answer stops looking.

Practising on questions written in exam format changes the way you read. It is not a matter of speed: it is the habit of looking for the word that restricts before choosing.

Calculation questions look thankless and are the most profitable: a Cp, a Cpk, a DPMO, a risk priority number, a takt time are always calculated the same way. Once the formula is automatic, those are points banked in advance, with no interpretation and no reading trap.

Many candidates set them aside when revising, precisely because they demand a concrete effort where reading a course gives the impression of progressing. The result is a preparation that gives up the easiest points.

The threshold to reach is not statistical mastery: it is knowing how to set up the calculation without hesitating over what goes in the numerator.

The last mechanism encompasses the other three. A preparation made only of reading gives a feeling of mastery that nothing verifies, and that feeling is misleading: rereading a definition you understand does not prove that you will know how to apply it.

The only way to know is to get things wrong before the exam. A low score on a mock test is not a bad sign, it is information — and it is exactly the information a candidate who merely rereads will never have before the day itself.

Timed mode adds the last dimension: time management is something you work on, and discovering on exam day that you are spending four minutes on a question is a nasty surprise that costs several points.