The Graph Vault
Packet / Part IV · Exam Lab
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The Graph Vault

Blank-paper recall · 30 core diagrams
If you remember one thing

Both exams pay 4 points a time for “draw and label”. It is the densest scoring in the course and it is pure recall. A diagram only scores when axes, every curve, the equilibrium and every shaded region are all named.

Work this list on blank paper. Draw it, label it, then open the checklist and compare.

Recall drills · draw each from memory
micro coreDraw from blank: (1) bowed PPC with efficient, unattainable and recession points; (2) supply and demand with a shortage and a surplus; (3) consumer and producer surplus; (4) deadweight loss from under- and over-production.
Checklist
  • PPC: axes are two goods. Point on the curve, point beyond it, point inside it. Slope = minus the opportunity cost of the horizontal good.
  • S&D: axes P and Q. Shortage and surplus drawn as horizontal gaps at off-equilibrium prices.
  • Surplus: CS above price under demand; PS below price above supply. Label demand as D, MB and supply as S, MC.
  • DWL: triangle between the curves, point at the efficient quantity, opening toward the actual quantity. Works in both directions.
interventionsDraw from blank: (5) binding price ceiling with shortage and DWL; (6) tax wedge with revenue and DWL; (7) tax incidence under elastic vs inelastic demand; (8) subsidy with government cost and DWL.
Checklist
  • Ceiling: horizontal line below P₁. Quantity traded reads off supply, not demand. Shortage is the horizontal gap.
  • Tax: vertical wedge of height = tax. Three prices marked — buyers pay, sellers keep, original. Revenue is a rectangle; DWL is the triangle to its right.
  • Incidence: two panels. Steep demand ⇒ consumer price rises nearly the full tax, small DWL. Flat demand ⇒ producers absorb it, big DWL.
  • Subsidy: quantity past Q₁. Government rectangle exceeds the surplus gained; the difference is the triangle.
firmsDraw from blank: (9) competitive firm at MR = MC; (10) MC crossing ATC at its minimum with the profit rectangle; (11) long-run industry supply; (12) monopoly with MR, DWL and the competitive benchmark.
Checklist
  • Competitive firm: MR flat at P. q where MC = MR. Lowercase letters for the firm, uppercase for the market.
  • ATC: U-shaped, MC cutting it exactly at the bottom. Profit is a rectangle, height (P − ATC), width q.
  • LR supply: horizontal at min ATC with identical firms; upward sloping when firms differ in productivity.
  • Monopoly: MR shares demand's intercept and is twice as steep. Q from MR = MC, then P read up on demand. Competitive Q where MC meets D. DWL between them.
households & externalitiesDraw from blank: (13) budget constraint with an income shift and a price pivot; (14) total vs marginal utility; (15) negative externality with the corrective tax; (16) positive externality with the corrective subsidy.
Checklist
  • Budget line: intercepts Income/P on each axis, slope −Px/Py. Income shifts parallel; a price change pivots around the other good's intercept.
  • Utility: total increasing and concave; marginal falling beneath it.
  • Negative externality: SMC above PMC. Q* < Q₁. Tax equal to external MC at Q* shifts supply onto SMC.
  • Positive externality: SMB above PMB. Q* > Q₁. Subsidy equal to external MB shifts demand onto SMB.
factors & tradeDraw from blank: (17) labor market with MRPL; (18) skill-biased technological change in two panels; (19) EITC; (20) investment demand against r; (21) PPC with CPC; (22) export and import goods with a world price; (23) tariff welfare with both DWL triangles.
Checklist
  • Labor: axes W and L. Demand labelled MRPL = MPL × MR — write the formula on the curve.
  • Skill bias: two panels, demand out only in the high-skill panel.
  • EITC: labor supply shifts out; market wage falls; workers get W₂ + credit.
  • Investment: axes I and r, downward sloping. Tax credit shifts out, pessimism shifts in.
  • CPC: straight line, slope = −terms of trade, tangent to the PPC, lying outside it.
  • Tariff: two horizontal price lines. Revenue over remaining imports. Two DWL triangles, d and f.
macroDraw from blank: (24) Keynesian Cross with equilibrium; (25) a PAE shift showing the multiplier; (26) fiscal offset; (27) the Fed's reaction function; (28) return to potential; (29) the market for dollars; (30) S + NKI = I.
Checklist
  • Keynesian Cross: axes Y and PAE. 45° line labelled Y = PAE. PAE line with intercept = autonomous spending, slope = mpc. Slope must be visibly less than 45°.
  • Multiplier: vertical drop = the shock; horizontal move in Y is larger. Annotate both.
  • Reaction function: axes π and r, upward sloping, crossing a horizontal r* line at πTARGET. Shifting it up lowers long-run inflation.
  • Return to potential: PAE shifting until it crosses the 45° line exactly at Y*.
  • FX: axes are quantity of dollars and price of dollars in foreign currency. Demand = foreigners buying US; supply = Americans buying abroad.
  • S + NKI = I: axes r* and quantity. Investment downward, S + NKI upward.