How Should We Evaluate a Supply-Side Policy Package?
Supply-side policies
What you will learn
- Choose policies that address the binding production constraint and coordinate their timing.
- Apply the model to an original scenario and justify its limits.
Essential definitions
- Demand-side spillover
- An effect on current expenditure arising from a policy primarily designed for another objective.
- Supply-side spillover
- An effect on productive capacity or costs arising from a policy primarily designed for another objective.
Start from the binding constraint
The binding constraint is the obstacle most limiting an activity. If firms cannot find skilled workers, cheaper finance alone may not help. If workers are qualified but cannot reach jobs, transport may matter more than another training course. Identify the problem using evidence before choosing a policy category.
Policies can complement each other. Broadband may be more valuable with digital training and competitive access. Training may work better with childcare and job placement. A package should explain these links rather than collecting unrelated measures under a general promise of growth.
Compare market incentives with direct intervention
Competition policy, useful deregulation and tax incentives can draw on firms' information and profit incentives. Their results depend on entry, market power, environmental costs and unequal starting resources. Revenue lost through tax relief has an opportunity cost, and displaced workers may need support.
Education, healthcare, research and infrastructure can address underinvestment, external benefits and coordination problems. Their effectiveness depends on selection, delivery, accountability and time. Compare actual alternatives under the same budget and objective, rather than an ideal private response against a poorly run public programme or the reverse.
Coordinate demand and supply over time
Use real GDP horizontally and the price level vertically on AD–AS. A public project can shift AD right while it is built, before it shifts LRAS or the Keynesian capacity boundary. A temporary spending stimulus may use idle capacity without raising potential. Explain which mechanism applies at each stage.
Automation can raise productivity while displacing workers; weaker rules can lower private costs while increasing pollution. Judge growth alongside employment transitions, income distribution and environmental sustainability. Demand support and social protection can help during adjustment, but require financing. Recommend a sequence, identify likely delays and state which outcomes would show that the package is addressing the original constraint.
Policy mechanisms at a glance
Each chain is conditional: higher capacity supports sustainable growth, but weak demand can still limit actual output.
Personal income tax cuts
Market-basedHigher after-tax reward → possible extra hours/participation → more effective labor supply → LRAS may rise
Evaluate: The income effect may offset work incentives; AD may rise first.
Corporate tax cuts
Market-basedHigher expected post-tax return → more investment → more capital/productivity → LRAS right
Evaluate: Investment is not guaranteed; profits taxes are not automatically marginal costs.
Labor-market reforms
Potentially bothBetter matching/mobility → fewer unfilled jobs → more effective labor use → SRAS/LRAS may rise
Evaluate: Public job-matching services and regulatory reforms use different approaches.
Lower minimum wage
Market-basedLower binding wage floor → possible lower hiring costs → more employment/output → SRAS may rise
Evaluate: Depends on market structure; lower wages can worsen poverty and need not increase employment under monopsony.
Reduced union power
Market-basedLess bargaining pressure → possible lower unit costs → SRAS may rise
Evaluate: Training, cooperation and worker protections may suffer; effects are contested.
Lower unemployment benefits
Market-basedLarger incentive to accept work → possible improved matching → more labor used → capacity may rise
Evaluate: Requires jobs and suitable skills; reduced support can hinder search and raise poverty.
Deregulation
Market-basedFewer unnecessary barriers → lower compliance/entry costs → efficiency and entry → SRAS then possibly LRAS right
Evaluate: Removing useful safety/environment rules can impose external costs.
Privatization
Market-basedOwnership incentives plus competition → possible restructuring/investment → efficiency → SRAS/LRAS may rise
Evaluate: Ownership transfer alone has no immediate supply effect; monopoly and access risks remain.
Trade liberalization
Market-basedLower barriers → cheaper inputs and competition → lower costs/innovation → SRAS and possibly LRAS right
Evaluate: Some industries contract; retraining and adjustment take time.
Education and training
InterventionistPublic skills investment → better relevant skills → higher productivity → LRAS right over time
Evaluate: Short courses may help early; schooling effects take years and depend on quality.
Healthcare investment
InterventionistBetter health access → fewer absences → participation/productivity → effective capacity rises
Evaluate: Cost, prevention, quality and access shape the gains.
Infrastructure investment
InterventionistRepairs/new networks → fewer bottlenecks → lower unit costs → SRAS and later LRAS right
Evaluate: Planning and construction take time; spending may raise AD first.
Technology, R&D and physical capital support
InterventionistPublic support → innovation/adoption/capital → greater productivity → LRAS right
Evaluate: Research can fail; complementary skills and additionality matter.
Evaluation matrix
- Time lags
- Repairs may help quickly; education and research often take years. Does this address the immediate problem?
- Government cost and opportunity cost
- What is forgone when spending rises or tax revenue falls? Consider financing and targeted alternatives.
- Magnitude and effectiveness
- Is the relevant constraint skills, capital, demand or institutions? Participation and additionality matter.
- State of the economy
- Extra capacity does not automatically fill a demand shortfall. Near capacity, productivity gains can ease inflation pressure.
- Labor/product-market flexibility
- Workers need mobility and firms need access to finance; rigidities can delay gains.
- Income inequality
- Who receives tax savings or loses income support? Access to training may be unequal.
- Workers and job security
- Restructuring can displace workers; weigh flexibility against protections and bargaining power.
- Environmental consequences
- Lower compliance costs may externalize pollution; well-designed standards can encourage innovation.
- Political feasibility
- Benefits may arrive after an election; distribution of costs affects support.
- Government failure
- Poor information, capture or weak procurement may waste resources.
- Short versus long run
- Separate early AD spending effects, SRAS cost effects, and later LRAS capacity effects.
Potential growth and long-run supply
LRAS moves from Yp=100 to Yp=120. Holding AD P=180−0.8Y fixed, the long-run price level is 84 at exactly the new potential output. The adjusted SRAS₂ passes through that long-run equilibrium; the adjustment path is not instantaneous.
More or better factors, technology and stronger institutions increase sustainable capacity. LRAS moves right. The final long-run equilibrium is on the new LRAS, not beyond potential output.
How to draw it and model assumptions
- Draw vertical LRAS₁ and LRAS₂.
- Intersect each with AD to mark initial E1 and new E2 at their respective capacities.
- Distinguish higher capacity from a temporary movement toward existing capacity.
New-classical long run: flexible input prices and output at potential. AD is held fixed to isolate the supply change; actual growth also depends on demand.
Demand management: fiscal and monetary policy
AD: P = 180 − 0.8Y. SRAS: P = 20 + 0.8Y. E2: Y=100, P=100. The final equilibrium closes the initial gap at Yp=100.
Expansionary monetary or fiscal policy raises spending and AD; contractionary policy lowers it. Closing a recessionary gap can raise output and employment, while closing an inflationary gap restrains price pressure.
How to draw it and model assumptions
- Select the initial recessionary or inflationary position.
- Shift AD toward the intersection of SRAS and LRAS.
- Mark initial E1 and final E2; compare the price level and real output at these intersections.
Short-run upward SRAS; potential output fixed. Policy transmission, confidence, import leakages and time lags determine the size of the actual AD shift.
Long-term shifts of Keynesian AS
Capacity rises from 120 to 144. AD remains P = 180 − 0.8Y. Initially Y=108.33, P=93.33; after the capacity change Y=119.39, P=84.49. On the rising segment AS₂ is P = Y/1.2 − 15.
Investment in productive capacity moves the rising and full-capacity portions of Keynesian AS right. At a given level of AD, output can be higher and price pressure lower; in a deep recession an increase in capacity alone may leave actual output unchanged.
How to draw it and model assumptions
- Draw the initial three-section AS curve.
- Move the bottleneck and vertical capacity sections right to show more capacity.
- Keep AD fixed and compare initial E1 with new E2.
Fixed AD, hypothetical capacity expansion with the flat-section price floor unchanged. Idle resources and sticky input prices persist in the low-output segment.
Apply and evaluate
- A successful package addresses binding constraints and coordinates timing, competition, capabilities and protection during adjustment.
Common misconceptions
- Supply-side policy can affect AD, and demand-side policy can affect future supply through investment.
Knowledge check
Why might a productive-capacity increase fail to reduce current cyclical unemployment?
Real-world application
Funding workforce skills
6 April 2017: The UK government launched its apprenticeship levy on 6 April 2017 to help fund apprenticeship training.
Model application: relevant training may raise worker productivity and reduce skills mismatch, expanding productive capacity over time. Evaluate training quality, employer participation, time lags and who bears the financing cost. An announced programme is evidence of a policy intervention, not proof that its intended productivity gains occurred.
UK government, New levy to double annual investment in home-grown skills ↗Historical evidence checked 9 October 2026. The model interpretation is an original teaching application.
What to remember
Choose policies that address the binding production constraint and coordinate their timing. Assess demand, supply, distribution and environmental effects separately before judging the whole package.
Completion is your own reflection on learning, not a test score. Syllabus references: 3.7.10, 3.7.11, 3.7.12, 3.7.13, 3.7.14.
Sources and applications
Lessons in this section
Guest progress is saved on this browser. Log in to save across devices; import is optional.