2026-W28
Misunderstandings in behavioural assumptions and public‑goods are the week's weakest areas
Aggregate quiz activity shows strong performance on supply and tax mechanics but recurring errors on behavioural assumptions, public goods and substitution/income effects.
Published July 19, 2026
Average score
86.8%
Question accuracy
85.8%
Total attempts
49
Unique participants
11
Average time per question
61.6 s
1. Weekly Overview
Supply/tax questions were answered well; behavioural assumptions and market‑failure concepts need targeted review.
Students scored highly overall (average score ~87%), with consistent correct answers on supply responses and complements. The clearest weaknesses are short conceptual questions about bounded selfishness, public goods and positive externalities, plus some confusion around substitution and income effects.
Student takeaway: Focus revision on behavioural assumptions (bounded selfishness), public goods and externalities, then practice demand-shift reasoning (substitution/income effects).
2. Key Patterns
Main Insights
Bounded selfishness and behavioural assumptions caused the largest single miss-rate
The item on 'bounded selfishness' had a 0% correct rate on multiple attempts, indicating a gap in understanding behavioural assumptions about preferences and social motives.
Advice: Re-read the definition and examples of bounded selfishness; practice short answer questions that ask you to contrast bounded selfishness with pure self-interest.
Public goods and externalities are a cluster of recurring errors
Questions on why public goods cause market failure and on positive externalities of production showed low correct rates (40% and 33% respectively), suggesting uncertainty about non-excludability, non-rivalry and welfare effects.
Advice: Practice categorising goods (excludable/non-excludable, rival/non-rival) and map each to the reason the market fails; sketch supply/demand and welfare diagrams for externalities.
Substitution and income effects caused hesitation
Items on the substitution effect and on demand shifts from income changes had mixed accuracy (50–57%) and relatively long times, showing students pause when decomposing price/income changes.
Advice: Work step-by-step: separate substitution effect (relative price change) from income effect (real purchasing power), and practice short numerical examples and labelled demand diagrams.
3. Revision Plan
Priority Areas
Bounded selfishness and behavioural assumptions · 2.4
Zero correct responses indicate a conceptual gap on how behaviour departs from pure self-interest.
Action: Review definitions and in-class examples; answer 5 short prompts contrasting bounded selfishness with selfish rationality.
Public goods and market failure · 2.9
Multiple incorrect answers show misunderstanding of non-excludability and non-rivalry implications.
Action: Classify example goods, draw diagrams showing free-rider problems, and summarise two policy responses.
Externalities of production and policy instruments · 2.8
Low correct rate on positive externalities suggests weak links between externality types and welfare/policy.
Action: Practice 3 short case studies: identify externality, show welfare loss/gain, suggest corrective policy.
Substitution vs income effect and demand shifts · 2.1
Mixed accuracy and longer response times indicate hesitation when decomposing effects.
Action: Do stepwise diagram practice and 5 numerical substitution/income effect problems.
Supply responses to taxes and relative price changes · 2.2
This is a relative strength but worth quick revision to consolidate high performance on tax/supply mechanics.
Action: Quickly redraw supply shifts for different tax and relative price scenarios; explain direction of shift in one sentence each.
4. Question Evidence
Featured Questions
Most Wrong Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| What is meant by 'bounded selfishness'? | Microeconomics | 2.4 | 3 | 0.0% | 100.0% | 9.9 s |
| Why do public goods often lead to market failure? | Microeconomics | 2.9 | 5 | 40.0% | 60.0% | 10.2 s |
| What is the substitution effect when the price of a good falls? | Microeconomics | 2.1 | 6 | 50.0% | 50.0% | 9.2 s |
| What happens to the demand curve when there is an increase in consumer income for a normal good? | Microeconomics | 2.1 | 7 | 57.1% | 42.9% | 12.8 s |
| What is a positive externality of production? | Microeconomics | 2.8 | 3 | 33.3% | 66.7% | 6.2 s |
Most Correct Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| What happens to the demand for bicycles if the price of bicycle helmets (a complement) rises? | Microeconomics | 2.1 | 12 | 100.0% | 0.0% | 13.2 s |
| Suppose beef and pork are substitutes, while beef and barbecue sauce are complements. The price of pork rises and the price of barbecue sauce also rises. If the substitution effect from pork to beef is known to be stronger than the negative effect from the higher barbecue sauce price, what is the net effect on the demand for beef? | Microeconomics | 2.1 | 12 | 100.0% | 0.0% | 30.7 s |
| The government introduces a new indirect tax on hotel stay. What happens to the hotel industry's supply curve? | Microeconomics | 2.2 | 14 | 85.7% | 14.3% | 1.0 min |
| The government raises the indirect tax on sugary drinks. What happens to the market supply of sugary drinks? | Microeconomics | 2.2 | 10 | 100.0% | 0.0% | 13.1 s |
| The price of apples rises while the price of oranges remains unchanged. Many farmers can switch between producing apples and oranges using the same land. What happens to the market supply of oranges? | Microeconomics | 2.2 | 10 | 100.0% | 0.0% | 24.4 s |
Most Time Spent Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| What is the purpose of regulation in government intervention? | Microeconomics | 2.7 | 3 | 100.0% | 0.0% | 162.3 min |
| How can tradable permits help reduce pollution? | Microeconomics | 2.8 | 3 | 100.0% | 0.0% | 3.6 min |
| In an open economy the marginal propensity to save (MPS) is 0.25, the marginal propensity to tax (MPT) is 0.15 and the marginal propensity to import (MPM) is 0.10. Calculate the Keynesian multiplier. | macroeconomics | 3.6 | 3 | 66.7% | 33.3% | 2.9 min |
| Which of the following is an example of an indirect tax? | Microeconomics | 2.7 | 3 | 100.0% | 0.0% | 1.6 min |
| The government introduces a new indirect tax on hotel stay. What happens to the hotel industry's supply curve? | Microeconomics | 2.2 | 14 | 85.7% | 14.3% | 1.0 min |
5. Conclusion
Targeted concept work will close the gap
You performed well on supply and tax mechanics; prioritise short, focused revision on behavioural assumptions, public goods and externalities and practice decomposition of substitution and income effects to improve accuracy quickly.
Note: This weekly report is automatically generated and may contain mistakes. Always double-check key points before using them for revision.
This report summarises anonymized aggregate quiz activity from the indicated week and does not include individual student-level data.