Problem Solving and Critical Thinking
What this domain tests
This domain tests structured thinking: defining a problem, finding root causes, generating and evaluating options, implementing a fix and verifying the result.
Core ideas
- Define before solving: write the problem in measurable terms, including what, where, when, how much and who is affected. "Machine is bad" is not a problem statement; "Line 2 motor trips after 20 minutes at full load" is.
- Separate symptom from cause: a tripping breaker is a symptom; an overloaded motor is closer to the cause.
- 5 Whys: ask why repeatedly until the underlying system cause appears. Stop when the answer points to a process that can be changed.
- Fishbone diagram: group possible causes under categories such as man, machine, material, method, measurement and environment.
- Brainstorming: generate options without judging, then evaluate against criteria such as cost, safety, time and feasibility.
- PDCA: plan, do, check, act. Verification is part of the method, not an optional extra.
- Thinking biases: confirmation bias favours evidence that supports your first idea; anchoring sticks to the first number offered; availability bias overweights recent incidents.
Worked example
A compressor overheats and shuts down. Symptom fix: reset the trip, which fails again. 5 Whys: Why hot? Low cooling airflow. Why low airflow? Clogged intake filter. Why clogged? No filter cleaning schedule. Why no schedule? Maintenance plan omits it. Why omitted? Plan was never updated after a relocation. Action: clean or replace the filter, add the task to the plan with a frequency, assign an owner and check temperature for a week. Reasoning: the filter is the immediate cause, but the missing schedule is the system cause that would otherwise repeat the failure.
Mark-losing traps
- Jumping to a solution before defining the problem.
- Fixing the symptom and closing the case.
- Brainstorming and judging at the same time.
- Ignoring data that contradicts your preferred answer.
- Implementing a fix without verifying the result.