ECC3841 Network Economics
The Complete Exam Bible · S2 2026ECC3841 Overview
- Monash University
- Semester 2 2026
- Level 3
- Final examination
ECC3841 Network Economics studies how the pattern of connections changes economic behavior. The course begins with graphs, paths, components, degree distributions and centrality. It then asks why links form, how peers affect choices, when diffusion crosses a threshold and how similar people sort into ties.
- Assessment Exercise 35%, Presentation 15%, Examination 50%.
- Final focus Written problems draw on lecture notes and tutorial material.
- Core method Represent, solve, check and interpret the network counterfactual.
- Past papers Available finals show recurring games, learning and contagion question types.
What you get in the full ECC3841 Exam Bible
- 10 chapters, 42 pages — every examinable topic
- 24 original practice questions, each with a model answer in the 3 - Examination format
- 10 worked examples, solved the way ECC3841 marks
- 10 computed figures, redrawn from the course’s own numbers
- Exam-morning plan for the 3 - Examination (50%) — what to revise last, where marks are lost
Free on this page: assessment table, chapter map, one worked example, key terms, FAQ. The rest is in the full exam bible.
How ECC3841 is assessed
| Component | Weight | Format |
|---|---|---|
| 1 - Exercise | 35% | Current Moodle detail: in-class quiz 10%, presentation slides 5%, final written report 20%. A separate schedule file gives a different internal split, so use the live task entries for submission planning. |
| 2 - Presentation | 15% | Three in-class group presentations, each worth 5%, across the project sequence. |
| 3 - Examination | 50% | Traditional written final based on lecture notes and tutorial material, held during the final examination period. |
What other students are asking about ECC3841
- Where can I find lecture notes or study guides for ECC3841 at Monash?
- The ECC3841 study guide in AskSia Library covers Network Economics in 10 chapters, with the assessment table, a chapter-by-chapter topic map, key terms and a worked example, free to read on this page.
- Is there a final exam in ECC3841, and how much is it worth?
- Yes. In the offering this AskSia Library guide is built from, 3 - Examination carries 50% of the ECC3841 mark; the full split is 1 - Exercise 35%, 2 - Presentation 15%, 3 - Examination 50%.
- What does ECC3841 cover on network formation and stability?
- In AskSia Library's ECC3841 guide, the Network Formation and Stability chapter explains block models, small worlds, preferential attachment and pairwise incentives.
- What does ECC3841 cover on peer effects and network games?
- In AskSia Library's ECC3841 guide, the Peer Effects and Network Games chapter explains identification, strategic interaction, equilibrium centrality and policy counterfactuals.
- What does ECC3841 cover on contagion and diffusion?
- In AskSia Library's ECC3841 guide, the Contagion and Diffusion chapter explains thresholds, reproduction numbers, compartment models and adoption curves.
What ECC3841 covers
Move from graph representation and centrality to formation, peer effects, diffusion and applied network policy. Each chapter links definitions to an original worked calculation.
Network Foundations and Centrality
Graphs, paths, components, degree distributions and four centrality measures.Network foundations turn a relationship into a graph. Begin by stating the nodes, what a link means and whether direction matters.
- Nodes, links and directed versus undirected adjacency
- Paths, geodesics, components and the giant component
- Degree and degree distributions
- Closeness as reciprocal distance
- Betweenness as shortest-path brokerage
- Eigenvector centrality and important neighbors
Network Formation and Stability
Block models, small worlds, preferential attachment and pairwise incentives.Network formation links observed structure to a process.
- Type-dependent link probabilities in block models
- Correct same-type and cross-type opportunity counts
- Small-world rewiring and shortcut paths
- Preferential attachment and degree inequality
- Private benefits and costs of links
- Nash link choices and bilateral consent
Peer Effects and Network Games
Identification, strategic interaction, equilibrium centrality and policy counterfactuals.Peer effects require a channel and an identification strategy. Endogenous effects run from peers outcomes, contextual effects from peers characteristics and correlated effects from shared environments. Network games then model how actions interact.
- Endogenous, contextual and correlated effects
- Reflection and friendship selection
- Strategic complements and substitutes
- Best replies and simultaneous equilibrium
- Katz-Bonacich centrality
- Positive spillovers and planner solutions
Contagion and Diffusion
Thresholds, reproduction numbers, compartment models and adoption curves.Contagion and diffusion connect network reachability to dynamic thresholds. Epidemic models compare transmission with recovery, while protection reduces the effective reproduction number.
- Giant-component thresholds
- Basic and effective reproduction numbers
- Protection and herd thresholds
- SIR compartment flows
- SIS reinfection dynamics
- Bass innovation and imitation channels
Homophily and Segregation
Opportunity-adjusted mixing, choice, sorting and unequal access.Homophily is disproportionate linking among similar nodes relative to an opportunity baseline. Raw same-type counts can mislead when group sizes differ, so compare actual links with possible pairs or population composition.
- Same-type and cross-type link counts
- Opportunity denominators
- Basic and adjusted homophily
- Choice versus induced homophily
- Group-specific mixing rates
- Segregation and redundant information
Crime and Key Players
Peer complementarities, social multipliers and removal policies.Crime networks can change returns through learning, partnership, norms and perceived detection. Positive peer spillovers create strategic complements and a social multiplier.
- Peer learning and criminal collaboration
- Selection and shared neighborhood conditions
- Strategic complements in effort
- Walk-based equilibrium amplification
- Friendship and competition matrices
- Social multipliers
Education and Peer Identification
Reflection, correlated effects, network measurement and causal designs.Education networks illustrate the identification problem behind peer effects. Students outcomes can co-move because they influence one another, have peers with similar characteristics or share teachers and environments.
- Endogenous achievement effects
- Contextual peer characteristics
- Shared school and teacher inputs
- Reflection and simultaneity
- Friendship selection
- Random peer assignment
Financial Networks and Systemic Risk
Bank runs, insolvency thresholds, interbank cascades and regulation.Financial networks transmit distress because one banks liability is another banks asset. Portfolio losses reduce equity; default writes down creditor claims and can trigger further insolvency.
- Maturity mismatch and bank runs
- Liquidity versus solvency
- Outside and interbank assets
- Equity as a loss buffer
- Default recovery and creditor write-downs
- Cascade rounds
Development Through Social Networks
Jobs, migration, informal insurance, social learning and technology adoption.Development networks replace or supplement incomplete markets. Weak ties can carry nonredundant job and migration information; strong ties can provide money, housing and enforcement.
- Job information through contacts
- Weak and strong ties
- Migration information and assistance
- Informal insurance and commitment
- Correlated shocks
- Technology adoption and social learning
Pricing and Word-of-Mouth
Awareness, diffusion demand, advertising targets and marginal reach.Network pricing adds awareness to the firms demand problem. A lower price can raise direct purchases and encourage buyers to communicate, creating new informed demand.
- Initially unaware consumers
- Valuation and purchase choice
- Degree distributions
- Price and communication incentives
- Direct and diffusion demand
- Advertising reach
The applications show why the same toolkit matters for crime, education, banking, development and firm strategy.
The quantitative spine is consistent across topics. Define the network and its direction, choose the interaction term, write best replies or state transitions, solve with visible steps and interpret a counterfactual.
A node with many links is not automatically the fastest bridge, the most prestigious contact or the best policy target. The relevant ranking depends on the mechanism.
The final examination is worth half the unit and is described for this offering as a traditional written examination based on lecture notes and tutorial material.
Historical papers repeatedly mix network-game algebra, probability, financial balance-sheet calculations and evidence-based discussion. Their exact allocation can change, so use them to rehearse question types rather than predict the paper.
The official handbook and current Moodle page agree on three top-level components.
A separate schedule file conflicts with Moodle on the internal Exercise split, so check the live task entries when planning project work. This guide keeps the agreed top-level weights and explains the conflicting detail instead of inventing a reconciliation.
Worked example · free
Solve a two-agent network game and verify the equilibrium
- +2Substitute the second best reply into the first: x1 = 1.5 + 0.2(0.9 + 0.2x1) = 1.68 + 0.04x1.
- +1Rearrange: 0.96x1 = 1.68, so x1 = 1.75.
- +1Back-substitute: x2 = 0.9 + 0.2(1.75) = 1.25.
- +1Check: 1.5 + 0.2(1.25) = 1.75 and 0.9 + 0.2(1.75) = 1.25.
- +1Interpret: each agents effort raises the others best reply, so the direct baseline difference is amplified through feedback along the link.
Key terms
- Adjacency matrix
- A matrix recording which ordered or unordered node pairs are linked. Its symmetry depends on whether the network is directed.
- Geodesic
- The shortest path between two nodes, measured by the number of links used.
- Betweenness centrality
- A node ranking based on the share of other pairs shortest paths that pass through the node.
- Pairwise stability
- A link pattern where no endpoint wants to sever an existing link and no absent link benefits both endpoints.
- Strategic complements
- Actions for which a rise in neighbors activity raises an agents best reply.
- Katz-Bonacich centrality
- A walk-based centrality that weights direct and indirect network exposure with geometric decay.
- Reflection problem
- The simultaneity problem created when an individual affects peers while peers affect the individual.
- Reproduction number
- The expected number of secondary cases created under stated susceptibility and transmission conditions.
- Homophily
- Disproportionate linking among similar nodes relative to a stated opportunity baseline.
- Key player
- The node whose removal produces the largest reduction in total equilibrium activity under the model.
- Financial contagion
- A process in which one institutions losses or default reduce counterparties asset values and trigger further distress.
- Information cascade
- Sequential behavior in which public evidence becomes strong enough for later decision-makers to ignore private signals.
ECC3841 FAQ
How is the unit assessed?
The official structure is Exercise 35%, Presentation 15% and Examination 50%. Current Moodle places the quiz, slides and report inside the Exercise, while a separate schedule file gives a conflicting internal split, so use the live task entries for detailed submission planning.
What is known about the final format?
The current course note describes a traditional written examination based on lecture notes and tutorial material during the Monash final-exam period. Use the official exam notice for duration, venue and permitted-material rules because those operational details are not supplied in the captured course note.
Are past papers available?
The course area lists finals from 2023, 2024 and 2025. They show recurring question families such as network games, social learning, education peer effects and financial contagion, but their exact allocations should not be treated as a forecast of the current paper.
Which centrality measure should I use?
Choose from the mechanism. Degree measures direct contacts, closeness measures short access, betweenness measures brokerage on shortest routes and eigenvector centrality rewards links to important nodes. State the economic channel before calculating a ranking.
Why is peer correlation not enough?
Connected people can look alike because they influence one another, select similar peers or share teachers, neighborhoods and shocks. A causal peer-effect claim needs a design that separates endogenous influence from contextual and correlated effects.
Is the highest-degree node always the key player?
No. The key player is defined by the largest fall in total equilibrium activity after removal. Deletion changes the remaining network and everyone may adjust, so each candidate requires a reduced-network equilibrium calculation.
How should I solve a financial cascade?
Write assets and liabilities for each bank, compute initial equity, apply the direct portfolio shock, mark first-round defaults, apply recovery losses to creditors and repeat until no new default occurs. Debt direction and recovery assumptions control the result.
Questions students ask in each ECC3841 chapter
- Can two nodes lead different centrality rankings?
- Yes. Degree values immediate contacts, closeness values short access, betweenness values brokerage and eigenvector centrality values important neighbors. A bridge can have modest degree and high betweenness. In calculations, write the graph convention, denominator and economic interpretation before giving the final ranking. Chapter 01 · Network Foundations and Centrality
- Does a block model prove preference for similarity?
- No. Higher same-type link rates describe mixing after opportunity adjustment, but preferences, meeting opportunities and institutional sorting can create the same pattern. A complete response separates descriptive structure, private link incentives and the external effect on other nodes. Chapter 02 · Network Formation and Stability
- What is the reflection problem?
- My action can affect peers while peers actions affect mine, creating simultaneity. A within-group correlation alone cannot reveal the causal direction. Show the simultaneous equations or identifying variation explicitly so the claimed network mechanism can be audited. Chapter 03 · Peer Effects and Network Games
- What does a reproduction threshold tell me?
- It indicates whether a small infection tends to grow or contract near the relevant state. It does not by itself determine peak size, timing or final reach. Name the state transition, threshold comparison and model assumption before recommending a diffusion intervention. Chapter 04 · Contagion and Diffusion
- Why are raw link counts insufficient?
- Large groups have more possible same-type pairs. Opportunity-adjusted rates distinguish composition from unusually frequent same-type linking. Use opportunity-adjusted rates and identify the resource transmitted before drawing a segregation or welfare conclusion. Chapter 05 · Homophily and Segregation
- Why can crime cluster without peer influence?
- People may select similar associates, face common policing and labor-market conditions or share neighborhood shocks. A causal design must separate those factors. Recompute the reduced-network equilibrium and discuss identification, rewiring and displacement before giving policy advice. Chapter 06 · Crime and Key Players
- Why not regress grade on class average?
- The class average can reflect the students own grade, simultaneous responses, sorting and shared teacher quality. A leave-one-out measure and a credible design are needed. State the causal threat, design assumption, coefficient units and remaining boundary in the same answer. Chapter 07 · Education and Peer Identification
- How does default spread?
- A debtor stops paying all or part of an interbank liability, reducing the creditor banks asset value. If the write-down exceeds the creditors capital buffer, another default follows. Trace assets, liabilities, recovery and equity through complete rounds instead of inferring failure from arrows alone. Chapter 08 · Financial Networks and Systemic Risk
- Why do networks matter when markets are incomplete?
- They can transmit information, enforce transfers and provide assistance when formal credit, insurance and labor-market institutions are limited. Link the network channel to the missing market and state the condition that limits the benefit. Chapter 09 · Development Through Social Networks
- Why can a lower price increase awareness?
- More informed consumers may buy and communicate, spreading product information to friends and expanding the informed market. Compare incremental profit after conversion, unique reach, overlap, margin loss and campaign cost are all counted. Chapter 10 · Pricing and Word-of-Mouth
How to study for the exam
Start with representation and never repair it silently later. For graph questions, define the node set, link direction and matrix convention. For games, derive best replies and check the solved values by substitution. For diffusion, name the state and threshold comparison. For homophily, count possible pairs before comparing actual links.
For empirical questions, separate endogenous, contextual and correlated effects before describing the design. For financial networks, trace asset values through liabilities one round at a time. Use the available finals to time original questions by type, not to memorize stems. Keep a short error ledger organized by representation, equation, arithmetic and interpretation; the earliest failed layer is the one to fix.
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