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Now, consider the factors on the left-hand side of the equation one at a time, while holding the other factors constant.

As a first example, assume that the level of domestic investment in a country rises, while the level of private and public saving remains unchanged. The result is shown in the first row of [link] under the equation. Since the equality of the national savings and investment identity must continue to hold—it is, after all, an identity that must be true by definition—the rise in domestic investment will mean a higher trade deficit. This situation occurred in the U.S. economy in the late 1990s. Because of the surge of new information and communications technologies that became available, business investment increased substantially. A fall in private saving during this time and a rise in government saving more or less offset each other. As a result, the financial capital to fund that business investment came from abroad, which is one reason for the very high U.S. trade deficits of the late 1990s and early 2000s.

Causes of a changing trade balance
Domestic Investment   – Private Domestic Savings   – Public Domestic Savings   = Trade Deficit
I S (T – G) = (M – X)
Up No change No change Then M – X must rise
No change Up No change Then M – X must fall
No change No change Down Then M – X must rise

As a second scenario, assume that the level of domestic savings rises, while the level of domestic investment and public savings remain unchanged. In this case, the trade deficit would decline. As domestic savings rises, there would be less need for foreign financial capital to meet investment needs. For this reason, a policy proposal often made for reducing the U.S. trade deficit is to increase private saving—although exactly how to increase the overall rate of saving has proven controversial.

As a third scenario, imagine that the government budget deficit increased dramatically, while domestic investment and private savings remained unchanged. This scenario occurred in the U.S. economy in the mid-1980s. The federal budget deficit increased from $79 billion in 1981 to $221 billion in 1986—an increase in the demand for financial capital of $142 billion. The current account balance collapsed from a surplus of $5 billion in 1981 to a deficit of $147 million in 1986—an increase in the supply of financial capital from abroad of $152 billion. The two numbers do not match exactly, since in the real world, private savings and investment did not remain fixed. The connection at that time is clear: a sharp increase in government borrowing increased the U.S. economy’s demand for financial capital, and that increase was primarily supplied by foreign investors through the trade deficit. The following Work It Out feature walks you through a scenario in which private domestic savings has to rise by a certain amount to reduce a trade deficit.

Solving problems with the saving and investment identity

Use the saving and investment identity to answer the following question: Country A has a trade deficit of $200 billion, private domestic savings of $500 billion, a government deficit of $200 billion, and private domestic investment of $500 billion. To reduce the $200 billion trade deficit by $100 billion, by how much does private domestic savings have to increase?

Step 1. Write out the savings investment formula solving for the trade deficit or surplus on the left:

(X – M)  =  S +  (T – G)  – I

Step 2. In the formula, put the amount for the trade deficit in as a negative number (X – M). The left side of your formula is now:

–200  =  S + (T – G) – I

Step 3. Enter the private domestic savings (S) of $500 in the formula:

   –200  =  500  + (T – G) – I

Step 4. Enter domestic investment (I) of $500 into the formula:

       –200  =  500  + (T – G) – 500

Step 5. The government budget surplus or balance is represented by (T – G). Enter a budget deficit amount for (T – G) of –200:

      –200  =  500  + (–200) – 500

Step 6. Your formula now is:

(X – M)  =  S + (T – G) – I –200  =  500 + (–200) – 500

The question is: To reduce your trade deficit (X – M) of –200 to –100 (in billions of dollars), by how much will savings have to rise?

(X – M)  =  S + (T – G) – I –100  =  S + (–200)  –  500 600  =  S

Step 7. Summarize the answer: Private domestic savings needs to rise by $100 billion, to a total of $600 billion, for the two sides of the equation to remain equal (–100 = –100).

Questions & Answers

why should a firm close down when it's unable to pay it's variable cost?
what is oligopolistic competitive market?
exchange of goods and services between countries is call
Hosea Reply
foreign trade
what is constant opportunity cost
Tiffany Reply
Constant opportunity cost means the value of sacrifice remains constant in every step.
Gross Domestic Product GDP
Yusuf Reply
what is g d p
Jayapal Reply
gross daily performance
How best can a poor country respond to an economic crisis , what does it have to sacrifice.
Bah Reply
they should pay tax as progressive system and should make sacrifice for taxation of their income and land etc
how have the nations tries to solve the problem of scarcity in their economies?
Amani Reply
total concentration on to reduce the per unit cost of commodity by technically or whatever
explain what will happen to producer of green coconut now that we have to lockdown in the kingdom of tonga
Tuha Reply
the demand for coconut will decrease and supply increases which result in the decrease in the price of coconut and the coconut will be more elastic
tonga is producing more long run economic good explain the meaning of the statement and its implication on the tonga economy
Tuha Reply
Demand is the various quantities of goods and services that consumer(s)are willing and able to purchase at a price within a time
Muhammad Reply
What is demand
Mc Reply
demand relates with the need of people for their satisfaction.
demand is de amount of goods and services a consumer us willing to purchase at a given price over a given period of time
riDemand is the amount of good and services which consumers are willing and able to buy at a particular peroid of time and at a given price
Yes that is the tire thing
Demand is the quantity of goods and services which consumers are willing and able to purchase at a given price over a period of time
simply , Demand is the sum up of 1)- desire of the commodity 2)- purchasing power for that commodity
demand is the amount of goods and service wen consumers are willing and able to buy them at a give time
Distinguish between cross elasticity and income elasticity of demand
Ruth Reply
Distinguish between cross elasticity and income elasticity of demand
if change in the demand of the commodity with respect to change in demand of the substitute or other product called cross elasticity
and. if change in the demand of the commodity due to change in the income . called income elasticity
Cross elasticity of demand is the degree of responsiveness of quantity demanded of a commodity to a small change in price of another commodity whiles Income elasticity of demand is the degree of responsiveness of quantity demanded of a commodity to a small change in income of it's consumers
but these are book wordings
income elasticity of demand shows how quantity demanded changes due to changes in income on the other hand cross elasticity refers to how the quantity demanded of a particular good alers given a change in the price of another good.
what is the competitive demand
Adiza Reply
Competitive demand are those commodity dat are competitive in nature e.g the close up and my my toothpaste the increase in price of close up may bring abt decrease in demand of it and it will serve as increase in purchase of my my
With regards to coal shortage and manicipal debts the what form of intervention do you think Eskom can put in place.
kedibone Reply
economic growth of Bhutan
Nima Reply
please, explain all the mathematics terms used in economics
The answer is: little more than high school algebra and graphs.

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Source:  OpenStax, Principles of economics. OpenStax CNX. Sep 19, 2014 Download for free at http://legacy.cnx.org/content/col11613/1.11
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