ACCA PM Common Mistakes & Examiner Insights
PM rewards candidates who can both calculate and interpret. The examiner repeatedly flags the same technique errors — applied slightly wrong, or calculated correctly but not explained. These are the recurring ones.
1. Mix variance: actual total input at standard mix
Always calculate the mix variance on the actual total input in standard mix proportions. Getting the base wrong is the most common mix-and-yield error.
2. Label planning and operational variances correctly
Planning variance = original standard vs revised standard (uncontrollable). Operational variance = revised standard vs actual (management performance). Candidates swap them — be explicit about which is which.
3. Throughput: per bottleneck unit, not per labour hour
Throughput accounting ranks products by contribution per unit of the bottleneck resource, not per labour hour. Using the wrong basis gives the wrong ranking.
4. Learning curve: cumulative average time
The learning effect applies to the cumulative average time per unit, which falls by the learning rate each time output doubles. Apply the formula to the cumulative average, not the incremental unit, unless asked.
5. Target costing: cost gap is current minus target
The cost gap = current cost − target cost. Be ready to suggest realistic strategies to close it; the reduction methods are examinable, not just the number.
6. Transfer pricing: give both the minimum and maximum
Always state both the minimum the seller will accept (marginal cost + opportunity cost) and the maximum the buyer will pay (external price or net marginal revenue). Giving only one is a half answer.
7. Balanced scorecard: all four perspectives, linked to strategy
Name all four perspectives (financial, customer, internal process, learning and growth) and link each measure to the organisation's strategy. A generic list without that link under-scores.
8. Interpretation must use the scenario
Generic commentary scores poorly. Anchor every point of analysis in the specific numbers and context the question gives you.
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