Skip to main content

Macroeconomics: Gross Domestic Product (GDP)

As we previously saw, the circular flow model shows that all the spending in an economy will roughly equal all of the income received.
  • Every dollar spent on goods or services is money earned by either firms or household. Thus, a nation's total expenditure is equal to the nation's total income.
  • Everything bought was at some point was produced, a nation's (domestic) output is equal to national (domestic) income.
There are three methods for measuring a nation's total output:
  • Expenditure approach
  • Income approach
  • Output approach
Expenditure approach for estimating GDP:
  • Summing the spending on final new goods and services in a given year.
  • Final goods are ready for consumption. Goods used as input in order to produce another goods are not included (only the final product/good is).
There are four types of spending in a nation's output:
  • Consumption(C): spending made by domestic households on durable and non-durable goods and services in a given time.
  • Investment(I): spending by firms on capital equipment and by households on newly constructed homes.
  • Government spending(G): the government's expenditure on goods, services, and capital. Transfer payments are not included.
  •  Net exports(Xn=X-M): total income earned by the sales of exports minus total amount spent by domestic households and firms on imported goods and services.
   
Income approach for estimating GDP:

Estimates GDP by summing the income of households in the resource (factor) market. Remember that national output equals national income.
  • Wages: the payment households receive for providing labor, this also includes salary.
  • Interests: the payment for the use of capital by firms. Most of capital spending is paid for with money borrowed from banks. The money in banks is in part derived from household's savings.
  • Rent: the payment households receive in exchange for the use of their land.
  • Profit: residuals after a firm deducts its costs of production from its revenue. In our case, revenue can be defined as price  times output.
Output approach for estimating GDP:

The output approach sums the total value of all final goods and services produced by a country in a year.
  • This method sums the value of total output for various industries/ economic sectors.  One can find the value of total output by summing the output value for each sector of a nation's economy. This gives us the gross national product (GDP).
Notice that all three methods achieve the same result: GDP=national expenditure= national income. Furthermore, notice that for each method, imports (or foreign produced goods and services) are excluded from our calculation. For more information about this aspect I would suggest reading this article by Steven M. Suranovic.

Reference: Welker, Jason. AP Maroeconomics Crash Course. Research & Education Association (2014). p 64-69.

Comments

Popular posts from this blog

Macroeconomics: multiplier and crowding out effects

Multiplier effect: whenever   any of the components of AD increases, the increase in GDP will be greater than the initial increase in expenditures. The impact on GDP of a particular increase in spending depends on the proportion of the new income that is taken out of the system to the proportion that continues to circulate in the economy. The multiplier effect tells us the impact a particular change in one the components of AD will have on the total income (GDP).  Let k denote the spending multiplier, which is a function of MPC and MPS. The larger the marginal propensity to consume, the larger the spending multiplier. Notice that the larger the MPC, the greater the impact a particular change in the spending variables will have on the nation's GDP. The crowding out effect: If government spending increases without an increase in taxes, the government must borrow funds from the private sector to finance its deficit, thereby increasing the interest rate. This increase in interest ...

Exercise: inflation and GDP deflator

You have the following table containing information about country Y's GDP deflator, nominal, and real GDP. If the base year is 2015, fill in the blanks and then find the annual inflation rate for each year. Year  Nominal GDP  GDP Deflator  Real GDP 2015 $23,457 100 $23,457 2016 $25,752 ... $23,943 2017 $25,982 108.1 ... 2018 $26,016 ... $25,431.1 2019 $26,323 105.5 ... Solution: Year  Nominal GDP  GDP Deflator  Real GDP   Inflation rate 2015 $23,457 100 $23,457 n.a 2016 $25,752 107.6 $23,943 7.6% 2017 $25,982 108.1 $24,035.2 0.45% 2018 $26,016 102.3 $25,431.1 -5.37% 2019 $26,323 105.5 $24,950.6 3.13%  GDP deflator for the year 2018: Real GDP for the year 2017: General formula to find real GDP by re-arranging the GDP deflator formula: Notice that the sub-index i is for the year. The (annual) inflation rate is simply the growth rate of prices from a year to its previous year: Inflation rate of the year 2018: Notice that in 2018 country Y experienced...

Exercise: maximizing profit

Assume that you are the owner of a small business that produces T-shirts. Your the total revenue for your business can be modeled by the following equation: and your total cost corresponds to this function: Find the point at which your firm maximizes its profit. Then, find how much profit the firm if able to earn at that point. Using the total cost and total revenue functions we can set up the profit function: Then, realize that if you want to find the maximum profit, take the derivative of the function and set it up equal to zero, and solve for Q. This is equivalent of taking the derivative of the total cost and total revenue functions and setting them equal to each other. In this problem, I chose the latter option as it was explained in the previous lessons. Notice that profit is often denoted by a capital pi.  We are assuming that the TR>TC for some positive value, you can check for yourself. However, if we did not know that, we would first take the first ...