Public Policy
Last section, we talked about economic growth and how that's measured. Now, we have public policies that can directly or indirectly affect the economy. Public policies that affect productivity and employment affect real GDP per capita, and thus, economic growth. These policies can come in multiple different styles. In addition, if the government invests in the infrastructure and technology, this can constitute growth as well. This is why the government focuses a lot on research and development, in hopes that improvements in technology will bring out a strong economy.
Remember how in the last section we talked about how different factors affect productivity? Well now we're talking about how the government and policies can affect those factors, which was hinted last time.
Types of Public Policy
There are three types of public policy that can promote economic growth:
- Increase in education spending
- By increasing investment in the education of workers, those workers are more effective and can produce more. Improving human capital increases the quality of labor available, which causes an increase in economic growth.
- Increase in infrastructure spending
- For example, if the government sets up dependable transportation systems, then they are helping businesses get inputs to production, and get goods to customers. This means that government investment in infrastructure can increase productivity and reduce business costs, which shifts LRAS to the right and increases potential output and long-run economic growth. In the short run, higher government spending can also shift AD to the right.
- Policies that spur innovation
- By creating policies that promote innovation, the government can promote economic growth in the long-run. For example, the government can create policies that protect intellectual property (patents), which would give private companies a greater incentive to create that intellectual property. By promoting creativity and entrepreneurship, we will be able to increase real GDP in the long run.
- Increase labor force participation or employment
- Policies that encourage more people to work increase the amount of labor available in the economy. A larger labor force can increase real GDP and, if combined with better skills and capital, can contribute to long-run economic growth. This is different from productivity, which refers to output per worker.
Supply-Side Economics
Supply-side fiscal policies are government tax and spending policies intended to increase incentives to work, save, invest, and produce. In AP Macroeconomics, examples include cuts in personal income taxes, cuts in corporate taxes, and government spending that improves productivity, such as education, infrastructure, and research and development. These policies can affect aggregate demand in the short run and can increase aggregate supply and potential output over time.
In the short run, some supply-side fiscal policies can increase aggregate demand. For example, a cut in personal or business taxes raises disposable income or after-tax profits, which can increase consumption and investment, shifting AD to the right. In the short run, lower business taxes can also reduce production costs and increase SRAS. In the long run, these policies can increase investment in capital, labor force participation, and productivity, which shifts LRAS to the right and increases potential output (full-employment output).
If SRAS or LRAS shifts to the right, real GDP rises and downward pressure is placed on the price level. However, if tax cuts also increase aggregate demand in the short run, the price level may rise at first, so the overall price-level effect depends on which curve shifts more and over what time period.
Graphically, a tax cut can shift AD right in the short run because consumption and investment rise. If the policy also increases incentives to produce, SRAS may shift right in the short run. In the long run, successful supply-side policies shift LRAS to the right, showing an increase in potential output and long-run economic growth.
How to Graph Public Policy and Long-Run Growth
- Education, infrastructure, and technology investment: show LRAS shifting right because the economy's productive capacity increases. Real GDP rises in the long run.
- Tax cuts aimed at incentives: in the short run, AD may shift right because consumption and investment increase; SRAS may also shift right if production incentives improve. In the long run, LRAS shifts right if the policy increases labor force participation, capital formation, or productivity.
- Key AP takeaway: supply-side fiscal policy can affect AD, SRAS, and LRAS/potential output, depending on the policy and time horizon.
Many fiscal policies are discussed as demand-side policies because changes in government spending and taxes can shift aggregate demand. However, fiscal policy can also be supply-side when taxes or productive government spending are intended to increase incentives, productivity, and potential output.
Some economists argue that the government shouldn't manipulate AD too much. Instead, they believe the government shouldn't intervene on the economy as much. These economists believe that without governmental intervention, the economy will correct itself. However, when the economy seriously needs government help, these economists argue the government should focus more on supply rather than demand.
Supply-side economics emphasizes policies that increase incentives to produce, work, save, and invest. These policies may increase SRAS in the short run and LRAS in the long run. Some supply-side fiscal policies, such as tax cuts, may also increase AD in the short run by raising disposable income and after-tax profits, but AD does not automatically rise just because aggregate supply rises.
Saving and Investment
With lower personal taxes, household disposable income increases, which may increase saving. Greater saving can increase the supply of loanable funds, lower the real interest rate, and increase investment. With lower business taxes, firms keep more after-tax profit, which can also encourage investment. This is the intended supply-side effect, although economists disagree about how large these effects are in practice. In addition, supply side economists think we should have something called investment tax credit, which reduces a firm's taxes if it invests. Cool right?
Looking at the same effects at a different angle: if taxes are cut, more income is available for households and it increases spending. Then it'll increase the profits of the firms and increase producing! This would increase the productive capacity (PPF) and LRAS as well (remember, growth! 🌱)
Supply side economic policies increase investment and saving leading to growth
Demand Side of Things
Economists disagree about the size of the effects of supply-side policies, but AP Macroeconomics focuses on how these policies are intended to change incentives, output, and growth. Supply side economists, in order to support their claim, argue that supply side policies also increase demand as well.
- work incentive — lower taxes can increase the incentive to work because households keep more of each additional dollar earned. This can increase labor force participation, hours worked, and employment. However, lower taxes do not directly increase labor productivity; productivity rises more directly through improvements in education, training, capital, infrastructure, and technology.
- risk-taking and investment incentive — lower business taxes can increase expected after-tax returns, which may encourage firms and investors to undertake more investment projects.
Vocabulary
The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.
| Term | Definition |
|---|---|
| aggregate demand | The total quantity of goods and services demanded across an entire economy at different price levels. |
| aggregate supply | The total quantity of goods and services that producers are willing and able to supply at various price levels. |
| economic growth | An increase in the production of goods and services in an economy over time, measured by the growth rate of real GDP per capita. |
| incentives | Factors that motivate households and businesses to make economic decisions and take actions. |
| infrastructure | Basic physical systems and facilities, such as roads, bridges, and utilities, that support economic activity. |
| labor force participation | The percentage of the working-age population that is either employed or actively seeking employment. |
| long-run economic growth | The sustained increase in an economy's productive capacity and real GDP over an extended period of time. |
| potential output | The maximum level of real GDP an economy can produce when all resources are fully and efficiently utilized. |
| productivity | The amount of output produced per unit of input, such as output per worker or output per hour of labor. |
| public policies | Government actions and programs designed to influence economic outcomes and achieve specific economic objectives. |
| real GDP per capita | The total value of goods and services produced by an economy adjusted for inflation and divided by the population, used to measure economic growth. |
| supply-side fiscal policies | Government policies that focus on increasing aggregate supply through tax cuts, deregulation, or incentives to boost production, investment, and economic growth. |
| technology | Tools, techniques, and knowledge used in production that improve efficiency and output. |
Frequently Asked Questions
What is supply-side fiscal policy and how is it different from regular fiscal policy?
Supply-side fiscal policy is any government action that increases the economy’s productive capacity (LRAS and potential output) by changing incentives for firms and workers—for example, investment tax credits, lower marginal tax rates, education spending, R&D subsidies, infrastructure, deregulation, or immigration policy. Unlike “regular” (demand-side) fiscal policy—which uses government spending and taxes to shift aggregate demand (AD) and stabilize short-run output and prices—supply-side policies shift long-run aggregate supply rightward, raising real GDP per capita and productivity over time. On an FRQ you’d show AD/AS: supply-side policy shifts LRAS (and SRAS eventually) right, lowering price level and increasing full-employment output. Remember AP expectations: explain the incentives, link to potential output, and use correctly labeled graphs (Topic 5.7 CED). For a focused review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and drill practice questions (https://library.fiveable.me/practice/ap-macroeconomics).
How do government policies actually make the economy grow in the long run?
Government policy boosts long-run growth by raising productivity and potential output—not by moving AD like short-run stimulus. Policies that increase human capital (education, training), physical capital (investment tax credits, infrastructure spending), and technological progress (R&D subsidies, patent incentives) raise output per worker and shift LRAS/rightward. Policies that raise labor force participation (immigration policy, childcare supports) increase the workforce, so real GDP per capita can rise. Supply-side fiscal tools (tax incentives, investment tax credits, deregulation) change incentives for firms and households, raising investment and capital stock over time. On the AP exam you should show this with an AD/AS graph: an outward shift of LRAS (and the PPC) to represent higher potential output (Topic 5.7). For a quick review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO), Unit 5 overview (https://library.fiveable.me/ap-macroeconomics/unit-5), and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
I don't understand how investing in infrastructure affects GDP - can someone explain?
Investing in infrastructure raises GDP mainly by increasing productivity and the economy’s physical capital stock. Better roads, ports, broadband, and power reduce firms’ costs and travel/transport time, so firms can produce more with the same labor—that shifts long-run aggregate supply (LRAS) right and raises potential (real) GDP per capita (EK POL-4.A.1, EK POL-4.A.2). In the short run, infrastructure spending is also government expenditure that raises aggregate demand (AD) and real GDP while construction is active. Over time the supply-side effect dominates: higher productivity → higher potential output and lower inflationary pressure for a given AD. That’s why infrastructure is a supply-side fiscal policy (it affects incentives and capacity). On the AP exam you should be ready to show this with AD/SRAS/LRAS graphs in free-response (Skill 4). For a quick review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
What's the difference between policies that affect short-run growth vs long-run growth?
Short-run policies change aggregate demand and affect real GDP and the price level temporarily. Examples: fiscal stimulus or tighter monetary policy—these shift AD, moving you away from or toward potential output (SRAS × AD graph). On the AP exam you’ll often show this on an AD–SRAS–LRAS graph and explain short-run output/price changes (skill categories 3 & 4). Long-run policies change productivity and potential output (LRAS)—they’re about real GDP per capita and sustained growth. Examples: public investment in infrastructure, education (human capital), R&D/technology, investment tax credits, immigration or deregulation. These supply-side fiscal policies change incentives, raise capital or labor quality, shift LRAS (and the PPC) outward, and increase potential output rather than just price-level movements. Remember: supply-side fiscal policy can affect AD in the short run but its key AP role is shifting AS and raising potential output in the long run. For Topic 5.7 review, see the Fiveable study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
How do tax cuts on businesses shift the aggregate supply curve?
A business tax cut is a supply-side fiscal policy that lowers firms’ costs and raises after-tax returns to investment. In the short run it shifts short-run aggregate supply (SRAS) right (downward pressure on the price level and higher real GDP) because lower marginal costs let firms produce more at each price. If the tax cut increases business investment, capital stock, or productivity, it can also shift long-run aggregate supply (LRAS) right over time—raising potential output and long-run economic growth (real GDP per capita). On the AP exam, be ready to show this on an AD–SRAS–LRAS graph: SRAS → right immediately; LRAS → right only if the policy raises capital, tech, or labor incentives. For a quick review of supply-side policies and practice drawing these shifts, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and Unit 5 resources (https://library.fiveable.me/ap-macroeconomics/unit-5). For extra practice, try problems at (https://library.fiveable.me/practice/ap-macroeconomics).
Can you explain how labor force participation affects real GDP per capita?
Labor force participation (the share of working-age people who are employed or actively looking) affects real GDP per capita because it changes how much output is produced per person. If participation rises (more people working or searching), real GDP typically increases—and real GDP per capita rises even without higher productivity per worker—because more workers produce more total output divided by the population. Conversely, a falling participation rate (e.g., aging population, discouraged workers) lowers real GDP per capita unless productivity per worker rises enough to offset it. On the AP exam you should link this to growth drivers in the CED: changes in labor force participation are a supply-side influence on potential output (LRAS/PPC shifts). You can show it with an LRAS or PPC shift or explain it in words (free-response often asks for graphs). For more review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and practice questions (https://library.fiveable.me/practice/ap-macroeconomics).
I'm confused about how supply-side policies affect both aggregate demand AND aggregate supply at the same time
Supply-side fiscal policies (like tax cuts, investment tax credits, education or R&D spending) change incentives for households and firms—so they affect both AD and AS. - AD effect (short run): Lower business or income taxes raise after-tax profit and disposable income → more investment and consumption, so AD shifts right. - AS effect (short run and long run): Better incentives increase capital formation, productivity, and labor-force participation → SRAS can shift right (lower per-unit costs) and LRAS (potential output) definitely shifts right over time as the economy’s productive capacity grows. So on an AD–AS graph you often show AD shifting right immediately and LRAS shifting right gradually. Short run: real GDP and price level may rise. Long run: higher potential output (EK POL-4.A.1–4.A.3) with smaller or ambiguous price-level change. For graphs and AP-style practice, review Topic 5.7 (study guide: https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and try problems at https://library.fiveable.me/practice/ap-macroeconomics.
What are some real examples of government policies that actually increased economic growth?
Short answer: yes—governments have used policies that raised long-run growth by boosting productivity, labor force participation, physical/human capital, and technology. Concrete examples: - Big infrastructure builds (U.S. Interstate Highway System, 1956) lowered transport costs and raised productivity over decades—classic public investment raising potential output. - Massive human-capital investment (South Korea’s post-1960s education expansion) greatly increased labor productivity and GDP per capita. - R&D support and tax incentives (e.g., R&D tax credits used in many advanced economies) encourage technological progress and shift LRAS right. - Targeted supply-side fiscal changes like investment tax credits and pro-business regulatory reform have raised incentives to invest (effects depend on implementation and time horizon). On the exam, tie these to CED concepts: how policies affect productivity, LRAS/AD, and potential output (EK POL-4.A.1–4.A.3). For review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
How do I draw the LRAS curve shifting when the government invests in technology?
Draw the standard AD–SRAS–LRAS graph with price level on the vertical axis and real GDP on the horizontal. LRAS is a vertical line at potential output (Yf). When the government invests in technology (R&D, infrastructure), productivity rises → potential output increases. So shift the LRAS curve rightward (LRAS → LRAS2) and label the new full-employment output Yf2 to the right of Yf. Notes for the AP free-response: label axes and curves, and show directional change. Often SRAS can also shift right over time as lower per-unit costs follow technological improvement, but AD usually doesn’t move immediately from this policy (supply-side fiscal policy). Use CED terms: technological progress, productivity, potential output (EK POL-4.A.2/4.A.3). For a quick review and extra practice, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and unit practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
Why do supply-side economists think tax cuts will increase government revenue?
Supply-side economists argue tax cuts can raise government revenue because lower marginal tax rates increase incentives to work, save, and invest. That boosts labor supply and capital accumulation, shifting long-run aggregate supply (LRAS) rightward and increasing potential output. With more income and profits generated, the broader tax base can sometimes produce higher total tax receipts even at a lower rate (this idea is shown by the Laffer curve). In AP terms, supply-side fiscal policies change incentives, raising productivity and real GDP per capita over time (EK POL-4.A.1, EK POL-4.A.3). On the exam you might show this with an AD/AS graph: tax cuts → higher SRAS/LRAS (over time) and higher Y. For a deeper read and practice problems on Topic 5.7, see the Fiveable study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and unit overview (https://library.fiveable.me/ap-macroeconomics/unit-5).
What happens to potential output when the government improves infrastructure?
When the government improves infrastructure (roads, ports, broadband, power), it raises the economy’s productivity and physical capital—so potential output (the economy’s full-employment real GDP, Yf) increases. On AP graphs you’d show this as a rightward shift of the long-run aggregate supply (LRAS) curve and an outward shift of the production possibilities curve (PPC). This is a classic supply-side fiscal policy: public investment raises incentives and capacity for firms and workers, increasing real GDP per capita over time (EK POL-4.A.1 & EK POL-4.A.2). In the short run some AD effects may occur, but the key exam point is LRAS shifts right → higher potential output, lower long-run price pressure for a given AD. For more on this topic, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and Unit 5 review (https://library.fiveable.me/ap-macroeconomics/unit-5). Practice AP-style problems at (https://library.fiveable.me/practice/ap-macroeconomics).
How do policies that affect productivity show up on the production possibilities curve?
Policies that raise productivity shift the economy’s production possibilities curve (PPC) outward—meaning the economy can produce more of both goods. Examples: public investment in infrastructure, education (human capital), R&D/technology, and pro-immigration or tax incentives for investment increase physical or human capital and technology, raising potential output. On AP graphs you’ll show an outward shift of the PPC and, equivalently, a rightward shift of long-run aggregate supply (LRAS)—both represent higher potential GDP per capita and long-run growth (EK POL-4.A.1–4.A.3). Supply-side fiscal policies (tax credits, deregulation) operate by changing incentives to invest or work, moving PPC/LRAS out over time. For FRQs you may be asked to draw and label these shifts (Skill 4). For more examples and exam practice, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO), Unit 5 overview (https://library.fiveable.me/ap-macroeconomics/unit-5), and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
I need help understanding how education spending counts as economic growth policy
Spending on education is a classic supply-side policy because it raises human capital and productivity—which increases real GDP per capita and long-run economic growth. Better schooling or job training makes workers more productive, which shifts the economy’s LRAS (and the PPC) to the right. Public education counts as public investment (like infrastructure or R&D): it increases the capital of the workforce, raises potential output, and can boost labor force participation over time. On the AP exam, you should be able to (a) explain this verbally and (b) show it on a free-response graph by shifting LRAS right and explaining higher potential output. Examples of supply-side fiscal tools: higher public education spending, education tax credits, or loans for training—all change incentives and raise long-run aggregate supply. For more review, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO) and practice problems (https://library.fiveable.me/practice/ap-macroeconomics).
What's the connection between supply-side fiscal policy and the Laffer curve?
Supply-side fiscal policy (tax cuts, tax credits, deregulation) aims to raise productivity, labor supply, and investment so LRAS and potential output shift right. The Laffer curve is a related idea: it graphs tax rate vs. tax revenue and shows revenue is zero at 0% and 100% tax rates, with a peak somewhere in between. Supply-siders use the Laffer logic to argue that lowering high marginal tax rates can increase incentives to work/save/invest, so GDP and tax revenue might rise if you're on the “right” side of the peak. But the peak’s location is empirical and uncertain—cuts can also reduce revenue and crowding-in effects aren’t guaranteed. On the AP exam, you might need to draw AD/SRAS/LRAS shifts to show long-run growth effects and explain the incentive channel; you could also sketch a Laffer curve and state that its peak is indeterminate. For the Topic 5.7 study guide see (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO). For unit review and practice problems visit (https://library.fiveable.me/ap-macroeconomics/unit-5) and (https://library.fiveable.me/practice/ap-macroeconomics).
How do I know if a policy question is asking about short-run or long-run effects on growth?
Short-run vs. long-run: look for the time language and the mechanism. If the question talks about changes in AD (spending, interest rates, taxes) or immediate output/price effects, it’s usually short-run—you’ll analyze AD and SRAS shifts and cyclical unemployment. If it mentions productivity, capital, human capital, infrastructure, technology, or “over time”/“sustained growth,” it’s long-run—you’ll shift LRAS (potential output) or the PPC. Supply-side fiscal policies (tax incentives, R&D, education) affect both: short-run via incentives to AD/AS, long-run by changing potential output (EK POL-4.A.1–4.A.3). On the exam, draw AD/SRAS/LRAS: short-run effects move AD or SRAS; long-run effects shift LRAS (vertical) and the PPC outward. For more examples and practice, see the Topic 5.7 study guide (https://library.fiveable.me/ap-macroeconomics/unit-5/public-policy-economic-growth/study-guide/UwgO2pbKel9Sq6KXtEVO), Unit 5 overview (https://library.fiveable.me/ap-macroeconomics/unit-5), and lots of practice problems (https://library.fiveable.me/practice/ap-macroeconomics).