ACCA Applied Knowledge · Management Accounting · Sampling methods

A manufacturer produces items on a production line and a quality inspector checks every 25th item starting from a random point. Unknown to the inspector, a machine fault causes a defect on every 25th item produced. What is the main weakness of the sampling method illustrated?

The weakness is that systematic sampling can be biased when the population has a regular pattern matching the sampling interval. Here every 25th item is checked and every 25th item is faulty, so the sample would be unrepresentative of the whole production.

1. ASystematic sampling may be biased if the population has a regular pattern matching the intervalCorrect
2. BSimple random sampling cannot be used on production lines
3. CStratified sampling gives unequal chances of selection to all items
4. DCluster sampling requires a complete sampling frame of every item