MATSEC IM Economics common mistakes
MATSEC IM Economics · Understand the traps and how to avoid them.
Defining a term (e.g. opportunity cost, elasticity, inflation) by restating the word or giving a circular definition instead of stating the precise economic relationship.
Candidates memorise labels from revision lists without learning the underlying relationship, so under exam pressure they can only rephrase the term itself.
What to do instead
For each key term, write a one-sentence definition that names the variables and the relationship (e.g. 'opportunity cost is the value of the next best alternative forgone when a choice is made'), then test it by asking whether someone who has never seen the term could apply it to a new example.
Drawing supply and demand diagrams with unlabelled axes, no equilibrium point, and no indication of which curve has shifted, then writing a conclusion that does not match the diagram.
Diagrams are treated as decoration rather than as an argument; candidates sketch quickly to fill space and never check that the written answer and the diagram tell the same story.
What to do instead
Adopt a fixed diagram routine: label both axes with the variable and units, label each curve, mark the original and new equilibrium with dotted lines and P/Q values, and write one sentence linking the shift to the new price and quantity. Practise until the routine is automatic.
Confusing a movement along a demand or supply curve with a shift of the curve, and giving a price change as the cause of a shift.
The distinction hinges on the ceteris paribus assumption, which candidates often recite but do not apply when classifying a scenario.
What to do instead
Before answering, ask 'is the change in price of this good itself, or in something else?' If it is the good's own price, it is a movement; if it is income, tastes, related-good prices, costs, technology or expectations, it is a shift. Sort ten mixed scenarios into the two categories and justify each.
Calculating price elasticity of demand as a simple percentage change without the correct base, and then interpreting a coefficient of, say, 0.4 as 'inelastic supply' or ignoring the sign convention.
The formula is recalled loosely, and the interpretation step is skipped because the arithmetic feels like the end of the question.
What to do instead
Use the midpoint formula unless told otherwise, show the substitution line, and always finish with an interpretation sentence: 'PED = -0.4, so demand is price inelastic; a 10% price rise reduces quantity demanded by about 4% and total revenue rises.' State that the negative sign is conventionally ignored when describing elasticity.
Describing market failure by listing examples (pollution, smoking, congestion) without identifying the specific source of failure, the divergence between marginal social and marginal private cost or benefit, and the resulting welfare loss.
Textbook examples are easier to recall than the underlying welfare analysis, so answers stay descriptive and never reach the analytical marks.
What to do instead
For every market-failure question, structure the answer as: source of failure, MSC/MPC or MSB/MPB divergence, over- or under-production relative to the social optimum, deadweight loss, then a policy evaluated against that specific divergence.
Writing evaluation that is a list of generic 'however' points ('it depends on elasticity', 'there may be time lags') without linking them to the specific market, magnitudes or time horizon in the question.
Candidates learn evaluation phrases as a template and deploy them regardless of context, which earns little credit for analysis.
What to do instead
For each evaluative point, add the mechanism and a condition: instead of 'it depends on elasticity', write 'a congestion charge will cut traffic substantially only if demand for peak commuting is price inelastic in the short run but becomes more elastic as commuters relocate or change hours'. Aim for two developed evaluative points rather than five undeveloped ones.
Treating macroeconomic objectives as independent and asserting that a policy achieving one objective necessarily harms another, without explaining the transmission mechanism or the short-run versus long-run distinction.
Conflicts such as the Phillips curve trade-off are memorised as slogans, and candidates do not trace the chain from policy instrument to intermediate variable to final objective.
What to do instead
Write out the chain explicitly for each conflict, e.g. 'lower interest rates -> higher consumption and investment -> upward pressure on aggregate demand -> demand-pull inflation if output is near capacity'. Then state the conditions under which the trade-off weakens, such as spare capacity or anchored inflation expectations.
Presenting national income statistics (GDP, GDP per capita, the multiplier) without stating what they measure, what they exclude, and why the figure may misrepresent living standards.
Definitions and limitations are studied as separate topics, so candidates do not connect the measurement question to the policy or comparison question being asked.
What to do instead
Keep a standing checklist for any GDP-based question: excludes non-market output, the informal economy and leisure; ignores distribution and environmental costs; per capita figures hide inequality; purchasing power differences affect international comparisons. Cite at least two limitations relevant to the specific question asked.
Describing a government policy or intervention without stating its objective, its mechanism and at least one reason it may fail, so the answer reads as a news summary rather than economic analysis.
Candidates know the policy exists but have not practised the objective-mechanism-evaluation structure under timed conditions.
What to do instead
Use a three-part frame for every policy answer: objective (which market failure or macro target), mechanism (which incentive or curve it changes), and failure risk (information problems, administration costs, evasion, unintended distributional effects). Apply the frame to three policies in one sitting.
Running out of time because too long is spent on short definitional questions, leaving the final extended-response question answered in note form with no conclusion.
Candidates write everything they know on early questions and do not allocate time by mark weighting or rehearse full papers under timed conditions.
What to do instead
Before starting, convert the mark allocation into minutes (roughly one minute per mark plus reading time) and write the target finish time for each section. Practise at least two full papers under timed conditions, and train a habit of writing the final conclusion first as a one-line judgement, then building the argument towards it.