STPM Ekonomi 944 common mistakes
STPM Ekonomi 944 · Understand the traps and how to avoid them.
When a question says 'harga barang X meningkat', the candidate immediately labels the new point on the same demand curve as a movement along it (pergerakan sepanjang keluk permintaan) instead of shifting the curve for a substitute/complement or for income effects, and writes 'kuantiti diminta berkurang, keluk beralih' in the same answer.
Candidates memorise the phrase 'harga naik, permintaan turun' as a single rule and never build the two-step check: does the price change belong to the good itself (movement) or to a determinant of demand (shift)? Under exam time pressure the familiar phrase wins over the definitional distinction between permintaan and kuantiti diminta.
What to do instead
Before drawing any diagram, write one line: 'Harga barang itu sendiri?' If yes, draw arrows along the existing curve and label pergerakan. If the change is income, taste, price of another good, population or expectation, draw a brand-new curve and label peralihan. Practise ten short scenarios and force yourself to state which of the two labels applies before sketching, so the habit is automatic.
Calculating price elasticity of demand with the simple formula (ΔQ/Q ÷ ΔP/P) using the original values as the base, and reporting different elasticities for a price rise and the corresponding price fall over the same range, without noticing the inconsistency.
Textbooks present both the simple and the mid-point formulae, and candidates grab whichever appears first. They also treat elasticity as a single number rather than a range-dependent measure, so they do not see why direction matters.
What to do instead
Adopt the mid-point formula as the default: (%ΔQ using average Q) ÷ (%ΔP using average P). Show the averages explicitly in the working. Then state the interpretation in words: |E| > 1 anjal, |E| < 1 tak anjal, |E| = 1 anjal satu. Also practise classifying by total revenue: if price rises and revenue falls, demand is elastic.
In production and cost questions, drawing the marginal cost curve as U-shaped but placing it so that it crosses average variable cost and average total cost at their minimum points on the wrong side, or drawing MC below ATC when ATC is rising.
Candidates memorise 'MC cuts AC at minimum' as a slogan but do not connect it to the arithmetic: when MC is below AC, AC must be falling, and when MC is above AC, AC must be rising. Without that reasoning the diagram is drawn by imitation, and the crossing points drift.
What to do instead
Derive it once numerically: build a small table of Q, TC, MC, AC and watch AC fall while MC < AC and rise while MC > AC. Then draw the diagram from the table. In the exam, add two check marks: at the minimum of AC, MC = AC; to the left MC < AC, to the right MC > AC. Apply the same check to AVC.
Describing a perfectly competitive firm's long-run equilibrium as earning supernormal profit, or stating that a monopolist always produces at the minimum of the average cost curve, in an answer that otherwise draws the correct curves.
Candidates learn the short-run profit-maximising rule MR = MC and then apply it to every time horizon and every market structure. The long-run entry/exit adjustment and the monopolist's lack of a supply curve are the parts most often skipped in revision.
What to do instead
Build a one-page comparison grid with rows for number of firms, price taker or maker, short-run profit possibility, long-run profit, and efficiency (allocative and productive). For each cell write the reason, not just the answer. In essays, always start by naming the time period and the structure before stating the profit outcome.
Computing national income by adding up all sales values of firms (including intermediate goods) or by summing incomes without adjusting for transfer payments, and then treating the total as GDP without checking whether it is at market prices or factor cost.
The three methods (output, income, expenditure) are taught as separate recipes, so candidates do not internalise that they must give the same total and that double counting and transfer payments are the two classic leaks. The market price versus factor cost adjustment (indirect taxes minus subsidies) is easily forgotten.
What to do instead
For every calculation, first write which method you are using and its adjustment line: output method subtract intermediate goods; income method exclude transfer payments and add net factor income from abroad for GNP; expenditure method use only final goods. Then state explicitly 'pada harga pasaran' or 'pada kos faktor' and apply the tax/subsidy bridge. Cross-check the total against a second method when data allow.
Explaining inflation by listing causes (demand-pull, cost-push, imported inflation) without linking each to the correct policy instrument, and answering a question about inflation with a description of deflationary gap policy or vice versa.
Candidates revise causes and remedies as two separate lists and never pair them. Under time pressure they write every policy they remember, including ones that would worsen the stated problem, hoping the marker will find something correct.
What to do instead
Make a two-column table: cause on the left, matching policy on the right, with the transmission chain written out (for example demand-pull: government cuts spending, aggregate demand falls, price level falls). In the exam, open the answer by identifying the type of inflation from the stimulus, then select only policies that attack that type, and state the mechanism in one sentence each.
Treating the money multiplier and the credit creation process as 'banks lend out all deposits', so the candidate writes that a RM1,000 deposit creates RM1,000 of new loans, ignoring the reserve ratio and the cash drain.
The process is taught as a formula (1/r) without the step-by-step balance-sheet logic, so candidates cannot reconstruct it when the question changes the reserve ratio or adds a currency drain. They also confuse the initial deposit with the total credit created.
What to do instead
Work through the rounds explicitly for a small reserve ratio: round 1 lends 900, round 2 lends 810, and so on, then sum the geometric series. Write the formula as total deposits = initial deposit × 1/r and total credit created = total deposits − initial reserves. Redo it with a 25 per cent reserve ratio and with a 10 per cent cash drain so the formula's assumptions are visible.
In international trade answers, confusing a tariff with a quota in the diagram, or stating that a tariff always improves a country's welfare because it protects domestic producers, without mentioning the deadweight loss triangles and the effect on consumers.
Protection is often taught as a list of advantages for domestic producers, and the welfare analysis is compressed into a single diagram that candidates reproduce without understanding the areas. The consumer loss and efficiency loss are then omitted from evaluation.
What to do instead
Learn the tariff diagram as five labelled areas: consumer surplus loss, producer surplus gain, government revenue, and two deadweight loss triangles (production distortion and consumption distortion). For each instrument, state the mechanism (tariff raises price and yields revenue; quota restricts quantity and yields quota rent). Evaluate with both gainers and losers before concluding.
Writing macroeconomic policy essays that list instruments (open market operations, reserve ratio, discount rate, government spending, taxation) without stating the direction of the change, the intermediate target, and the final objective, so the answer never says whether the instrument is raised or lowered or why.
Candidates memorise instrument names as a checklist and assume the marker will infer the direction. The transmission mechanism from instrument to aggregate demand to output and price level is the part they cannot reconstruct under pressure.
What to do instead
Use a fixed sentence template for every instrument: 'Untuk mengatasi [masalah], bank pusat [menaikkan/menurunkan] [instrumen], yang [mengurangkan/menambah] rizab bank perdagangan, seterusnya [menurunkan/menaikkan] kadar faedah, lalu [menambah/mengurangkan] pelaburan dan AD.' Fill it in for each instrument and check that the direction is consistent with the stated problem.
Answering 'beza antara KDNK dan KNK' or 'beza barang ekonomi dan barang percuma' with a single definition each and no example, no formula and no consequence, producing a two-line answer to a question worth several marks.
Candidates treat definition questions as low-value and rush them, not realising that STPM structured questions allocate marks for definition, example, formula or diagram, and implication. The habit of writing the shortest possible sentence costs marks that are easy to secure.
What to do instead
For every 'bezakan' or 'takrifkan' question, write four elements: definition of each term, the formula or boundary condition, one concrete Malaysian example, and one implication for policy or measurement. Practise on KDNK versus KNK, barang ekonomi versus barang percuma, and permintaan versus kuantiti diminta until the four-element structure is automatic.