Macroeconomics - The Multiplier Effect

The marginal propensity to consume (MPC) is equal to ΔC / ΔY, where ΔC is change in consumption, and ΔY is change in income. If consumption increases by eighty cents for each additional dollar of income, then MPC is equal to 0.8 / 1 = 0.8.

The expenditure multiplier is the ratio of the change in total output induced by an autonomous expenditure change.

Look Out!
In the Keynesian model, government and private investment spending are considered to be autonomous while consumption is not because it is a function of income.

Some consumption is considered to be autonomous. Even with no income, some consumption will occur (savings will need to be used). So the consumption function could be expressed as C = α + (β × Y), where α represents consumption that occurs regardless of income, β is the marginal propensity to consume and Y is income.

Why is there a multiplier effect?
Suppose a large corporation decides to build a factory in a small town and that spending on the factory for the first year is $5 million. That $5 million will go to electricians, engineers and other various people building the factory. If MPC is equal to 0.8, those people will spend $4 million on various goods and services. The various business and individual receiving that $4 million will in turn spend $3.2 million and so on.

If the marginal propensity to consume is equal to 0.8 (4 / 5), then the multiplier can be calculated as:

Multiplier = 1 / (1 - MPC) = 1 / (1 - 0.8) = 1 / 0.2 = 5

As a result of the multiplier effect, small changes in investment or government spending can create much larger changes in total output. A positive aspect of the multiplier effect is that macroeconomic policy can effect substantial improvements with relatively small amounts of autonomous expenditures. A negative aspect is that a small decline in business investment can trigger a larger decline in business activity and, thereby, create instability.

The previously mentioned formula for calculating the multiplier is a simplified one. Leakages (money spent, but not on domestic goods or domestic services) reduce the size of the multiplier. Examples of leakages include taxes and imports.

Another important point is that the multiplier effect takes time to work; months must pass before even half of the total multiplier effect is felt. Also, keep in mind that the multiplier effect can cause idle resources to be moved into production. If unemployment is widespread, then there should be little impact on resource prices.

Discretionary Fiscal Policy and Automatic Stabilizers
Related Articles
  1. Personal Finance

    How To Choose A Financial Advisor

    Many advisors display similar skillsets that can make distinguishing between them difficult. The following guidelines can help you better understand their qualifications and services.
  2. Investing

    Asset Manager Ethics: Investment Process and Actions

    Managers, in developing their investment process, need to determine some “general rules” that make it meaningful. We offer six.
  3. Professionals

    Career Advice: Financial Analyst Vs. Investment Banker

    Read an in-depth comparison about working as a Financial Analyst vs. working as an Investment Banker, two highly prestigious business careers.
  4. Professionals

    Advisors: Which Certifications Are Essential?

    The right advisor credentials can make all the difference, but wading through some 100 certifications can be a challenge. Here's some help.
  5. Investing Basics

    Asset Manager Ethics: Valuation Is A Tricky Business

    Asset managers must accurately represent all of a clients assets in the client portfolio. This can be tricky for unique and hard-to-value assets.
  6. Personal Finance

    Top 10 Most Valuable Sports Teams in 2015

    Cleats, pads and profits: we take a look at the top 10 most valuable sports teams in the world.
  7. Professionals

    Chinese Slowdown Affects Iron Ore Market

    The Chinese economy's ongoing slowdown is having a major impact on iron ore demand.
  8. Personal Finance

    Invest in Costco? First Understand Its Balance Sheet

    A strong balance sheet sets a company apart and boosts investor confidence. How healthy is Costco based on an analysis of its balance sheets from the last two years?
  9. Investing Basics

    Brokers and RIAs: One and the Same?

    Brokers and registered investment advisors have some key differences. Here's what you need to know.
  10. Professionals

    DCF Vs. Comparables: Which One To Use

    DCF and Comparables models are widely used in equity valuation. We explain the pros and cons of each method.
  1. Personal Financial Advisor

    Professionals who help individuals manage their finances by providing ...
  2. CFA Institute

    Formerly known as the Association for Investment Management and ...
  3. Chartered Financial Analyst - CFA

    A professional designation given by the CFA Institute (formerly ...
  4. Security Analyst

    A financial professional who studies various industries and companies, ...
  1. What are the differences between a Chartered Financial Analyst (CFA) and a Certified ...

    The differences between a Chartered Financial Analyst (CFA) and a Certified Financial Planner (CFP) are many, but comes down ... Read Full Answer >>
  2. How do I become a Chartered Financial Analyst (CFA)?

    According to the CFA Institute, a person who holds a CFA charter is not a chartered financial analyst. The CFA Institute ... Read Full Answer >>
  3. What types of positions might a Chartered Financial Analyst (CFA) hold?

    The types of positions that a Chartered Financial Analyst (CFA) is likely to hold include any position that deals with large ... Read Full Answer >>
  4. Who benefits the most from prepaid expenses?

    Prepaid expenses benefit both businesses and individuals. Prepaid expenses are the types of expenses that are bought or paid ... Read Full Answer >>
  5. If I am looking to get an Investment Banking job. What education do employers prefer? ...

    If you are looking specifically for an investment banking position, an MBA may be marginally preferable over the CFA. The ... Read Full Answer >>
  6. Can I still pass the CFA Level I if I do poorly in the ethics section?

    You may still pass the Chartered Financial Analysis (CFA) Level I even if you fare poorly in the ethics section, but don't ... Read Full Answer >>
Hot Definitions
  1. Capitalization Rate

    The rate of return on a real estate investment property based on the income that the property is expected to generate.
  2. Gross Profit

    A company's total revenue (equivalent to total sales) minus the cost of goods sold. Gross profit is the profit a company ...
  3. Revenue

    The amount of money that a company actually receives during a specific period, including discounts and deductions for returned ...
  4. Normal Profit

    An economic condition occurring when the difference between a firm’s total revenue and total cost is equal to zero.
  5. Operating Cost

    Expenses associated with the maintenance and administration of a business on a day-to-day basis.
  6. Cost Of Funds

    The interest rate paid by financial institutions for the funds that they deploy in their business. The cost of funds is one ...
Trading Center
You are using adblocking software

Want access to all of Investopedia? Add us to your “whitelist”
so you'll never miss a feature!