Comparing two explanations fairly means showing what each one fits in the evidence and what each leaves unexplained. It does not mean inventing reasons for what people did, or naming a preferred policy, when the question gave neither.
This lesson belongs to evidence-based economic answers. The habit of keeping facts and judgements apart comes from separating a model assumption from an observed fact.
What are the three steps?
First, state each explanation in one line. Second, list the supplied evidence that fits it. Third, name what the evidence does not show.
Then write one sentence on what extra information would separate the two. That sentence is what turns a list into a comparison.
Worked example: fewer bus riders in a fictional town
A fictional town’s daily bus riders fall from 5 000 to 4 400. In the same period the fare rises from RM2.00 to RM2.20. A local poll of 200 residents finds that 50 more of them now work from home than a year ago.
Explanation A: the higher fare reduced ridership. Explanation B: more working from home reduced ridership.
The fall in riders is 600 ÷ 5 000 × 100 = 12%, and the fare rise is 0.20 ÷ 2.00 × 100 = 10%.
| Explanation A: fare rise | Explanation B: working from home | |
|---|---|---|
| Fits the data | Fare rose 10%, riders fell 12% | 50 of 200 surveyed now work from home |
| What is missing | Which riders left, and why | How many of the 4 400 commute to work |
| What would separate them | Ridership by trip purpose | Ridership before and after for commuters only |
The data fits both. It cannot show how much of the 12% fall belongs to each, so a fair conclusion says that.
The mistake that costs marks
A common slip is to write “the operator raised fares to earn more profit, which drove riders away”. The question never gives the operator’s reason, so the motive is invented.
The fix is to describe the action without a reason: “The fare rose from RM2.00 to RM2.20.” Stay with what happened.
A second slip is to end with “so fares should be cut”. That is a policy preference, and the data does not support it, because working from home may explain part of the fall.
| Step | Wrong | Right |
|---|---|---|
| Operator’s action | Raised fares to earn more profit | Fare rose by RM0.20 |
| Choice between explanations | Fares are the cause | Data fits both, sizes unknown |
| Ending | Fares should be cut | More data on trip purpose would separate them |
Check yourself
A fictional cafe’s weekly sales fall from RM4 000 to RM3 400. Explanation A: a new cafe opened nearby. Explanation B: the cafe raised coffee prices from RM6 to RM7.
The cafe’s own records show the price rise and no data on other cafes. Write a fair comparison in three or four sentences.
Answer
The fall is 600 ÷ 4 000 × 100 = 15%, and the price rise is 1 ÷ 6 × 100 = 16.7%.
Model answer: “Sales fell 15% while the price of coffee rose by about 16.7%, which fits Explanation B. The records say nothing about other cafes, so Explanation A can be neither supported nor ruled out. Both could have contributed. Sales by customer type, or the number of customers before and after the new cafe opened, would help separate them.”
The answer does not state why the cafe raised its price, and it does not say what the cafe should do.
What to study next
Practise the full set with the cluster practice set, or return to developing a short causal chain with a stated limiting condition. The claim evidence and explanation revision desk helps you revise a paragraph.
If a teacher checking your comparison wording would help, see online one-to-one Economics tuition.