💡 Quick Exam Tip
Midweek reset — here's a IV. Quality Management Tools - Sampling \(Understand\) tip worth remembering.
A quality analyst decides that instead of inspecting every unit in a large batch, she will randomly select units across different production shifts, ensuring the sample represents variation from all shifts rather than being drawn only from whichever shift happens to be running when she checks. What sampling concept does this decision illustrate?
1️⃣ Random sampling alone, since selecting units at random is always sufficient regardless of the shift structure
2️⃣ 100% inspection, since checking multiple shifts is roughly equivalent to inspecting every single unit
3️⃣ Stratified sampling, because sampling from each shift subgroup captures variation a simple random sample might miss
4️⃣ Systematic sampling, since units are being selected at a fixed interval within each individual shift
👀 Think about it before you scroll for the answer...
✅ Correct answer: 3) Stratified sampling, because sampling from each shift subgroup captures variation a simple random sample might miss
Deliberately sampling across shift-based subgroups to ensure all sources of variation are represented is stratified sampling, one of the basic sampling techniques and when it's appropriate to use \(Domain IV.K\).
💡 Exam tip: Whenever a scenario mentions sampling across known subgroups \(shifts, categories, locations\) specifically to capture their variation, that's stratified sampling, not plain random sampling.
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August 31, 2026 28
