2026-W38
Struggling with combined supply–demand diagrams; core micro foundations remain strong
This week students showed high accuracy on basic micro concepts but had clear difficulty combining multiple supply/demand shifts and applying them in single diagrams.
Published September 27, 2026
Attempts (week)
176
Active students
41
Average score
81%
Question accuracy
80.7%
Avg time per question
51s
1. Weekly Overview
Diagrams with multiple simultaneous effects are the weakest area.
Aggregate results show excellent mastery of basic micro concepts (law of supply, shifts vs movements, equilibrium) but low accuracy on hard diagram questions that require combining supply/demand shifts and expectations or simultaneous policy and demand effects.
Student takeaway: Prioritise practicing multi-step supply and demand diagrams (unit 2.2) and short quantitative checks for supply-side calculations.
2. Key Patterns
Main Insights
Combining effects on one diagram is the clearest weakness
Hard diagram questions in Microeconomics (unit 2.2) had the lowest correct rates (0% and ~18%) and high attempt counts, indicating repeated difficulty drawing and labelling combined shifts (policy + expectations; cost-saving tech + cancellations).
Advice: Work step-by-step: (1) identify which curves move, (2) decide direction for each, (3) draw shifts one at a time, (4) mark new equilibrium and check welfare/quantity effects.
Strong mastery of core definitions and equilibrium reasoning
High accuracy (94–100%) on questions about the law of supply, movements vs shifts, the role of prices, and equilibrium shows reliable foundation knowledge in Units 2.1–2.3.
Advice: Keep practicing short definition-to-application questions to maintain speed and accuracy; use these strengths when tackling multi-effect diagrams by linking each shift to the core concept it reflects.
Long response times on some quantitative macro items suggest calculation or process hesitation
Certain macro calculation items (e.g., Keynesian multiplier) show low accuracy (40%) alongside unusually long average times, which may indicate students are unsure of the calculation steps or are pausing mid-attempt.
Advice: Practice a small set of core formulas (multiplier, real interest rate) with 3–4 timed worked examples to build procedure fluency and reduce on-question hesitation.
3. Revision Plan
Priority Areas
Combined supply & demand shifts (diagrams) · 2.2
Lowest correct rates on multi-effect diagram questions where students must combine policy, expectations, and cost changes.
Action: Practice 6–8 two-effect diagrams this week; annotate each step (which curve moves, why, direction, new equilibrium).
Deriving market supply from individual supply · 2.2
Moderate error rate on how individual supplies aggregate to market supply.
Action: Work through exercises that sum individual supply horizontally and compare to plotted market supply; do 4 short examples.
Producer surplus and equilibrium welfare · 2.3
Some incorrect answers on producer surplus interpretation and welfare implications.
Action: Draw supply/demand with producer surplus shaded in 5 examples, then explain changes when supply/demand shift.
Key macro formulas (multiplier, real interest rate) · 3.5–3.6
Low accuracy and long times on calculation items suggest procedural uncertainty.
Action: Do 6 timed formula drills (2 per formula) and write a one-line justification for each step.
4. Question Evidence
Featured Questions
Most Wrong Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| In a single diagram for streaming subscriptions, show the effects of a major cost-saving AI recommendation system and negative media coverage that makes some users cancel their subscriptions. | Microeconomics | 2.2 | 11 | 18.2% | 81.8% | 37.4 s |
| In a single diagram for solar panels, show the effects of a government production subsidy and rising expectations that future electricity prices will be much higher. | Microeconomics | 2.2 | 7 | 0.0% | 100.0% | 22.2 s |
| How is market supply derived from individual supply? | Microeconomics | 2.2 | 16 | 56.3% | 43.8% | 20.7 s |
| Which of the following would cause a shift in the supply curve? | Microeconomics | 2.2 | 16 | 62.5% | 37.5% | 24.1 s |
| Producer surplus refers to: | Microeconomics | 2.3 | 17 | 64.7% | 35.3% | 12.0 s |
Most Correct Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| What does the law of supply state? | Microeconomics | 2.2 | 19 | 94.7% | 5.3% | 10.0 s |
| What distinguishes a movement along the demand curve from a shift of the curve? | Microeconomics | 2.1 | 18 | 94.4% | 5.6% | 12.8 s |
| What is the role of prices in the price mechanism? | Microeconomics | 2.3 | 18 | 94.4% | 5.6% | 12.1 s |
| Which of the following would cause a shift in the demand curve for coffee? | Microeconomics | 2.1 | 17 | 94.1% | 5.9% | 16.6 s |
| What is true at the market equilibrium point? | Microeconomics | 2.3 | 15 | 100.0% | 0.0% | 15.6 s |
Most Time Spent Questions
| Question | Topic | Unit | Attempts | Correct | Wrong | Avg Time |
|---|---|---|---|---|---|---|
| What problem arises when people can consume a good without paying for it? | Microeconomics | 2.9 | 7 | 100.0% | 0.0% | 57.7 min |
| In a closed economy with no taxes or imports, households have a marginal propensity to consume (MPC) of 0.8. Calculate the Keynesian multiplier. | macroeconomics | 3.6 | 5 | 40.0% | 60.0% | 40.8 min |
| What happens to equilibrium price and quantity when demand increases? | Microeconomics | 2.3 | 13 | 61.5% | 38.5% | 27.3 min |
| A government bond yields a nominal return of 8% while inflation is running at 3%. Calculate the real interest rate. | macroeconomics | 3.5 | 5 | 100.0% | 0.0% | 21.2 min |
| Which of the following is a common feature of labour market reform under market-based supply-side policy? | Macroeconomics | 3.7 | 3 | 100.0% | 0.0% | 7.6 min |
5. Conclusion
Focus practice on multi-effect diagrams and a few core calculations
Use your strong core knowledge (definitions, equilibrium) as a scaffold: practice stepwise diagrams for combined shifts in 15–20 minute sessions and run short timed drills on supply aggregation and multiplier calculations to close the gap.
Note: This weekly report is automatically generated and may contain mistakes. Always double-check key points before using them for revision.
This report reflects anonymized aggregate quiz activity for the week and does not include any personal or identifiable student information.