A measured benefit cannot be set against a cost nobody measured. Report each separately, mark the gap, and keep your conclusion conditional.
This lesson is part of economic activity and environmental evidence. It leads into writing a balanced geographical conclusion.
What is the cancelling-out error?
It happens when a student sees figures for the benefit and none for the cost, then treats the cost as zero. The benefit then “wins” by default.
The data did not show the cost was small. It simply did not measure it.
Worked example: a shrimp pond project
This is an original case. A coastal project clears 50 hectares of mangrove for shrimp ponds.
| Item | Type | Evidence given |
|---|---|---|
| Income from shrimp | Benefit | RM900 000 a year |
| Jobs | Benefit | 120 jobs |
| Mangrove cleared | Cost | 50 hectares |
| Loss of storm protection | Cost | No figure given |
| Effect on fish nursery areas | Cost | No figure given |
Benefit per job: 900 000 ÷ 120 = RM7 500 of shrimp income per job.
The measured cost is 50 hectares. The other two costs are unmeasured. They are not zero.
A careful sentence: “The project brings RM900 000 a year and 120 jobs, whereas it removes 50 hectares of mangrove, and the data gives no figure for lost storm protection or fish nurseries, so the full cost cannot be compared with the benefit.”
The mistake that loses marks
The weak conclusion is “The benefits are large and the costs are small, so the project is worth it”. The costs were never shown to be small.
| Step | Wrong | Right |
|---|---|---|
| Missing cost | Treated as zero | Marked as unknown |
| Conclusion | Project is worth it | Benefit is clear, cost incomplete, so judgement is conditional |
The right version asks for more evidence, and it shows the marker that you read the table carefully.
How do I conclude with gaps?
Use a conditional structure: “If storm protection matters to the nearby village, the cost may be larger. If the pond site was already degraded, it may be smaller.”
Then say which data would settle it, for example the village’s flood record. The claim and evidence revision desk helps you check each statement.
Check yourself
A resort brings RM2 million a year and 80 jobs. It clears 10 hectares of coastal forest. No data is given on the forest’s role in stopping erosion. Write two sentences on benefit against cost.
Answer
“The resort brings RM2 million a year and 80 jobs, whereas it clears 10 hectares of coastal forest. The data gives no figure for erosion, so the environmental cost is not fully measured and a firm verdict cannot be given.”
Income per job is 2 000 000 ÷ 80 = RM25 000, but the cost side has no comparable figure.
What to study next
Finish with writing a balanced geographical conclusion from an original case. For a teacher to review your benefit and cost writing, see online one-to-one Geography tuition.