Page 1 Chapter 4 Chapter 4 Determination of Income and Determination of Income and Determination of Income and Determination of Income and Determination of Income and Employment Employment Employment Employment Employment We have so far talked about the national income, price level, rate of interest etc. in an ad hoc manner – without investigating the forces that govern their values. The basic objective of macroeconomics is to develop theoretical tools, called models, capable of describing the processes which determine the values of these variables. Specifically, the models attempt to provide theoretical explanation to questions such as what causes periods of slow growth or recessions in the economy, or increment in the price level, or a rise in unemployment. It is difficult to account for all the variables at the same time. Thus, when we concentrate on the determination of a particular variable, we must hold the values of all other variables constant. This is a stylisation typical of almost any theoretical exercise and is called the assumption of ceteris paribus, which literally means ‘other things remaining equal’. You can think of the procedure as follows – in order to solve for the values of two variables x and y from two equations, we solve for one variable, say x, in terms of y from one equation first, and then substitute this value into the other equation to obtain the complete solution. We apply the same method in the analysis of the macroeconomic system. In this chapter we deal with the determination of National Income under the assumption of fixed price of final goods and constant rate of interest in the economy. The theoretical model used in this chapter is based on the theory given by John Maynard Keynes. 4.1 AGGREGATE DEMAND AND ITS COMPONENTS In the chapter on National Income Accounting, we have come across terms like consumption, investment, or the total output of final goods and services in an economy (GDP). These terms have dual connotations. In Chapter 2 they were used in the accounting sense – denoting actual values of these items as measured by the activities within the economy in a certain year. We call these actual or accounting values ex post measures of these items. These terms, however, can be used with a different connotation. Consumption may denote not what people have actually consumed in a given year, but what they 2020-21 Page 2 Chapter 4 Chapter 4 Determination of Income and Determination of Income and Determination of Income and Determination of Income and Determination of Income and Employment Employment Employment Employment Employment We have so far talked about the national income, price level, rate of interest etc. in an ad hoc manner – without investigating the forces that govern their values. The basic objective of macroeconomics is to develop theoretical tools, called models, capable of describing the processes which determine the values of these variables. Specifically, the models attempt to provide theoretical explanation to questions such as what causes periods of slow growth or recessions in the economy, or increment in the price level, or a rise in unemployment. It is difficult to account for all the variables at the same time. Thus, when we concentrate on the determination of a particular variable, we must hold the values of all other variables constant. This is a stylisation typical of almost any theoretical exercise and is called the assumption of ceteris paribus, which literally means ‘other things remaining equal’. You can think of the procedure as follows – in order to solve for the values of two variables x and y from two equations, we solve for one variable, say x, in terms of y from one equation first, and then substitute this value into the other equation to obtain the complete solution. We apply the same method in the analysis of the macroeconomic system. In this chapter we deal with the determination of National Income under the assumption of fixed price of final goods and constant rate of interest in the economy. The theoretical model used in this chapter is based on the theory given by John Maynard Keynes. 4.1 AGGREGATE DEMAND AND ITS COMPONENTS In the chapter on National Income Accounting, we have come across terms like consumption, investment, or the total output of final goods and services in an economy (GDP). These terms have dual connotations. In Chapter 2 they were used in the accounting sense – denoting actual values of these items as measured by the activities within the economy in a certain year. We call these actual or accounting values ex post measures of these items. These terms, however, can be used with a different connotation. Consumption may denote not what people have actually consumed in a given year, but what they 2020-21 54 54 54 54 54 Introductory Macroeconomics had planned to consume during the same period. Similarly, investment can mean the amount a producer plans to add to her inventory. It may be different from what she ends up doing. Suppose the producer plans to add Rs 100 worth goods to her stock by the end of the year. Her planned investment is, therefore, Rs 100 in that year. However, due to an unforeseen upsurge of demand for her goods in the market the volume of her sales exceeds what she had planned to sell and, to meet this extra demand, she has to sell goods worth Rs 30 from her stock. Therefore, at the end of the year, her inventory goes up by Rs (100 – 30) = Rs 70 only. Her planned investment is Rs 100 whereas her actual, or ex post, investment is Rs 70 only. We call the planned values of the variables – consumption, investment or output of final goods – their ex ante measures. In simple words, ex-ante depicts what has been planned, and ex-post depicts what has actually happened. In order to understand the determination of income, we need to know the planned values of different components of aggregate demand. Let us look at these components now. 4.1.1. Consumption The most important determinant of consumption demand is household income. A consumption function describes the relation between consumption and income. The simplest consumption function assumes that consumption changes at a constant rate as income changes. Of course, even if income is zero, some consumption still takes place. Since this level of consumption is independent of income, it is called autonomous consumption. We can describe this function as: C C cY = + (4.1) The above equation is called the consumption function. Here C is the consumption expenditure by households. This consists of two components autonomous consumption and induced consumption (cY ). Autonomous consumption is denoted by C and shows the consumption which is independent of income. If consumption takes place even when income is zero, it is because of autonomous consumption. The induced component of consumption, cY shows the dependence of consumption on income. When income rises by Re 1. induced consumption rises by MPC i.e. c or the marginal propensity to consume. It may be explained as a rate of change of consumption as income changes. C MPC c Y ? = = ? Now, let us look at the value that MPC can take. When income changes, change in consumption ( ) C ? can never exceed the change in income ( Y) ? . The maximum value which c can take is 1. On the other hand consumer may choose not to change consumption even when income has changed. In this case MPC = 0. Generally, MPC lies between 0 and 1 (inclusive of both values). This means that as income increases either 2020-21 Page 3 Chapter 4 Chapter 4 Determination of Income and Determination of Income and Determination of Income and Determination of Income and Determination of Income and Employment Employment Employment Employment Employment We have so far talked about the national income, price level, rate of interest etc. in an ad hoc manner – without investigating the forces that govern their values. The basic objective of macroeconomics is to develop theoretical tools, called models, capable of describing the processes which determine the values of these variables. Specifically, the models attempt to provide theoretical explanation to questions such as what causes periods of slow growth or recessions in the economy, or increment in the price level, or a rise in unemployment. It is difficult to account for all the variables at the same time. Thus, when we concentrate on the determination of a particular variable, we must hold the values of all other variables constant. This is a stylisation typical of almost any theoretical exercise and is called the assumption of ceteris paribus, which literally means ‘other things remaining equal’. You can think of the procedure as follows – in order to solve for the values of two variables x and y from two equations, we solve for one variable, say x, in terms of y from one equation first, and then substitute this value into the other equation to obtain the complete solution. We apply the same method in the analysis of the macroeconomic system. In this chapter we deal with the determination of National Income under the assumption of fixed price of final goods and constant rate of interest in the economy. The theoretical model used in this chapter is based on the theory given by John Maynard Keynes. 4.1 AGGREGATE DEMAND AND ITS COMPONENTS In the chapter on National Income Accounting, we have come across terms like consumption, investment, or the total output of final goods and services in an economy (GDP). These terms have dual connotations. In Chapter 2 they were used in the accounting sense – denoting actual values of these items as measured by the activities within the economy in a certain year. We call these actual or accounting values ex post measures of these items. These terms, however, can be used with a different connotation. Consumption may denote not what people have actually consumed in a given year, but what they 2020-21 54 54 54 54 54 Introductory Macroeconomics had planned to consume during the same period. Similarly, investment can mean the amount a producer plans to add to her inventory. It may be different from what she ends up doing. Suppose the producer plans to add Rs 100 worth goods to her stock by the end of the year. Her planned investment is, therefore, Rs 100 in that year. However, due to an unforeseen upsurge of demand for her goods in the market the volume of her sales exceeds what she had planned to sell and, to meet this extra demand, she has to sell goods worth Rs 30 from her stock. Therefore, at the end of the year, her inventory goes up by Rs (100 – 30) = Rs 70 only. Her planned investment is Rs 100 whereas her actual, or ex post, investment is Rs 70 only. We call the planned values of the variables – consumption, investment or output of final goods – their ex ante measures. In simple words, ex-ante depicts what has been planned, and ex-post depicts what has actually happened. In order to understand the determination of income, we need to know the planned values of different components of aggregate demand. Let us look at these components now. 4.1.1. Consumption The most important determinant of consumption demand is household income. A consumption function describes the relation between consumption and income. The simplest consumption function assumes that consumption changes at a constant rate as income changes. Of course, even if income is zero, some consumption still takes place. Since this level of consumption is independent of income, it is called autonomous consumption. We can describe this function as: C C cY = + (4.1) The above equation is called the consumption function. Here C is the consumption expenditure by households. This consists of two components autonomous consumption and induced consumption (cY ). Autonomous consumption is denoted by C and shows the consumption which is independent of income. If consumption takes place even when income is zero, it is because of autonomous consumption. The induced component of consumption, cY shows the dependence of consumption on income. When income rises by Re 1. induced consumption rises by MPC i.e. c or the marginal propensity to consume. It may be explained as a rate of change of consumption as income changes. C MPC c Y ? = = ? Now, let us look at the value that MPC can take. When income changes, change in consumption ( ) C ? can never exceed the change in income ( Y) ? . The maximum value which c can take is 1. On the other hand consumer may choose not to change consumption even when income has changed. In this case MPC = 0. Generally, MPC lies between 0 and 1 (inclusive of both values). This means that as income increases either 2020-21 55 55 55 55 55 Income Determination the consumers does not increase consumption at all (MPC = 0) or use entire change in income on consumption (MPC = 1) or use part of the change in income for changing consumption (0< MPC<1). Imagine a country Imagenia which has a consumption function described by C=100+0.8Y . This indicates that even when Imagenia does not have any income, its citizens still consume Rs. 100 worth of goods. Imagenia’s autonomous consumption is 100. Its marginal propensity to consume is 0.8. This means that if income goes up by Rs. 100 in Imagenia, consumption will go up by Rs. 80. Let us also look at another dimension of this, savings. Savings is that part of income that is not consumed. In other words, S Y C = - We define the marginal propensity to save (MPS) as the rate of change in savings as income increases. S MPS s Y ? = = ? Since, S Y C = - , ( ) 1 Y C s Y Y C Y Y c ? - = ? ? ? = - ? ? = - Some Definitions Marginal propensity to consume (MPC): it is the change in consumption per unit change in income. It is denoted by c and is equal to C Y ? ? . Marginal propensity to save (MPS): it is the change in savings per unit change in income. It is denoted by s and is equal to 1 c - . It implies that 1 s c + = . Average propensity to consume (APC): it is the consumption per unit of income i.e., C Y . Average propensity to save (APS): it is the savings per unit of income i.e., S Y . 2020-21 Page 4 Chapter 4 Chapter 4 Determination of Income and Determination of Income and Determination of Income and Determination of Income and Determination of Income and Employment Employment Employment Employment Employment We have so far talked about the national income, price level, rate of interest etc. in an ad hoc manner – without investigating the forces that govern their values. The basic objective of macroeconomics is to develop theoretical tools, called models, capable of describing the processes which determine the values of these variables. Specifically, the models attempt to provide theoretical explanation to questions such as what causes periods of slow growth or recessions in the economy, or increment in the price level, or a rise in unemployment. It is difficult to account for all the variables at the same time. Thus, when we concentrate on the determination of a particular variable, we must hold the values of all other variables constant. This is a stylisation typical of almost any theoretical exercise and is called the assumption of ceteris paribus, which literally means ‘other things remaining equal’. You can think of the procedure as follows – in order to solve for the values of two variables x and y from two equations, we solve for one variable, say x, in terms of y from one equation first, and then substitute this value into the other equation to obtain the complete solution. We apply the same method in the analysis of the macroeconomic system. In this chapter we deal with the determination of National Income under the assumption of fixed price of final goods and constant rate of interest in the economy. The theoretical model used in this chapter is based on the theory given by John Maynard Keynes. 4.1 AGGREGATE DEMAND AND ITS COMPONENTS In the chapter on National Income Accounting, we have come across terms like consumption, investment, or the total output of final goods and services in an economy (GDP). These terms have dual connotations. In Chapter 2 they were used in the accounting sense – denoting actual values of these items as measured by the activities within the economy in a certain year. We call these actual or accounting values ex post measures of these items. These terms, however, can be used with a different connotation. Consumption may denote not what people have actually consumed in a given year, but what they 2020-21 54 54 54 54 54 Introductory Macroeconomics had planned to consume during the same period. Similarly, investment can mean the amount a producer plans to add to her inventory. It may be different from what she ends up doing. Suppose the producer plans to add Rs 100 worth goods to her stock by the end of the year. Her planned investment is, therefore, Rs 100 in that year. However, due to an unforeseen upsurge of demand for her goods in the market the volume of her sales exceeds what she had planned to sell and, to meet this extra demand, she has to sell goods worth Rs 30 from her stock. Therefore, at the end of the year, her inventory goes up by Rs (100 – 30) = Rs 70 only. Her planned investment is Rs 100 whereas her actual, or ex post, investment is Rs 70 only. We call the planned values of the variables – consumption, investment or output of final goods – their ex ante measures. In simple words, ex-ante depicts what has been planned, and ex-post depicts what has actually happened. In order to understand the determination of income, we need to know the planned values of different components of aggregate demand. Let us look at these components now. 4.1.1. Consumption The most important determinant of consumption demand is household income. A consumption function describes the relation between consumption and income. The simplest consumption function assumes that consumption changes at a constant rate as income changes. Of course, even if income is zero, some consumption still takes place. Since this level of consumption is independent of income, it is called autonomous consumption. We can describe this function as: C C cY = + (4.1) The above equation is called the consumption function. Here C is the consumption expenditure by households. This consists of two components autonomous consumption and induced consumption (cY ). Autonomous consumption is denoted by C and shows the consumption which is independent of income. If consumption takes place even when income is zero, it is because of autonomous consumption. The induced component of consumption, cY shows the dependence of consumption on income. When income rises by Re 1. induced consumption rises by MPC i.e. c or the marginal propensity to consume. It may be explained as a rate of change of consumption as income changes. C MPC c Y ? = = ? Now, let us look at the value that MPC can take. When income changes, change in consumption ( ) C ? can never exceed the change in income ( Y) ? . The maximum value which c can take is 1. On the other hand consumer may choose not to change consumption even when income has changed. In this case MPC = 0. Generally, MPC lies between 0 and 1 (inclusive of both values). This means that as income increases either 2020-21 55 55 55 55 55 Income Determination the consumers does not increase consumption at all (MPC = 0) or use entire change in income on consumption (MPC = 1) or use part of the change in income for changing consumption (0< MPC<1). Imagine a country Imagenia which has a consumption function described by C=100+0.8Y . This indicates that even when Imagenia does not have any income, its citizens still consume Rs. 100 worth of goods. Imagenia’s autonomous consumption is 100. Its marginal propensity to consume is 0.8. This means that if income goes up by Rs. 100 in Imagenia, consumption will go up by Rs. 80. Let us also look at another dimension of this, savings. Savings is that part of income that is not consumed. In other words, S Y C = - We define the marginal propensity to save (MPS) as the rate of change in savings as income increases. S MPS s Y ? = = ? Since, S Y C = - , ( ) 1 Y C s Y Y C Y Y c ? - = ? ? ? = - ? ? = - Some Definitions Marginal propensity to consume (MPC): it is the change in consumption per unit change in income. It is denoted by c and is equal to C Y ? ? . Marginal propensity to save (MPS): it is the change in savings per unit change in income. It is denoted by s and is equal to 1 c - . It implies that 1 s c + = . Average propensity to consume (APC): it is the consumption per unit of income i.e., C Y . Average propensity to save (APS): it is the savings per unit of income i.e., S Y . 2020-21 56 56 56 56 56 Introductory Macroeconomics 4.1.2. Investment Investment is defined as addition to the stock of physical capital (such as machines, buildings, roads etc., i.e. anything that adds to the future productive capacity of the economy) and changes in the inventory (or the stock of finished goods) of a producer. Note that ‘investment goods’ (such as machines) are also part of the final goods – they are not intermediate goods like raw materials. Machines produced in an economy in a given year are not ‘used up’ to produce other goods but yield their services over a number of years. Investment decisions by producers, such as whether to buy a new machine, depend, to a large extent, on the market rate of interest. However, for simplicity, we assume here that firms plan to invest the same amount every year. We can write the ex ante investment demand as I = I (4.2) where I is a positive constant which represents the autonomous (given or exogenous) investment in the economy in a given year. 4.2 DETERMINATION OF INCOME IN TWO-SECTOR MODEL In an economy without a government, the ex ante aggregate demand for final goods is the sum total of the ex ante consumption expenditure and ex ante investment expenditure on such goods, viz. AD = C + I. Substituting the values of C and I from equations (4.1) and (4.2), aggregate demand for final goods can be written as AD = C + I + c.Y If the final goods market is in equilibrium this can be written as Y = C + I + c.Y where Y is the ex ante, or planned, ouput of final goods. This equation can be further simplified by adding up the two autonomous terms, C and I , making it Y = A + c.Y (4.3) where A = C + I is the total autonomous expenditure in the economy. In reality, these two components of autonomous expenditure behave in different ways. C , representing subsistence consumption level of an economy, remains more or less stable over time. However , I has been observed to undergo periodic fluctuations. A word of caution is in order. The term Y on the left hand side of equation (4.3) represents the ex ante output or the planned supply of final goods. On the other hand, the expression on the right hand side denotes ex ante or planned aggregate demand for final goods in the economy. Ex ante supply is equal to ex ante demand only when the final goods market, and hence the economy, is in equilibrium. Equation (4.3) should not, therefore, be confused with the accounting identity of Chapter 2, which states that the ex post value of total output must always be equal to the sum total of ex post consumption and ex post investment in the economy. If ex ante demand for final goods falls short of the output of final goods that the producers have planned to produce in a given year, equation (4.3) will not hold. Stocks will be piling up in the warehouses which we may consider as unintended accumulation of inventories. It should be noted that inventories or stocks refers to that part of output produced which is not sold and therefore remains with the firm. Change in inventory is called 2020-21 Page 5 Chapter 4 Chapter 4 Determination of Income and Determination of Income and Determination of Income and Determination of Income and Determination of Income and Employment Employment Employment Employment Employment We have so far talked about the national income, price level, rate of interest etc. in an ad hoc manner – without investigating the forces that govern their values. The basic objective of macroeconomics is to develop theoretical tools, called models, capable of describing the processes which determine the values of these variables. Specifically, the models attempt to provide theoretical explanation to questions such as what causes periods of slow growth or recessions in the economy, or increment in the price level, or a rise in unemployment. It is difficult to account for all the variables at the same time. Thus, when we concentrate on the determination of a particular variable, we must hold the values of all other variables constant. This is a stylisation typical of almost any theoretical exercise and is called the assumption of ceteris paribus, which literally means ‘other things remaining equal’. You can think of the procedure as follows – in order to solve for the values of two variables x and y from two equations, we solve for one variable, say x, in terms of y from one equation first, and then substitute this value into the other equation to obtain the complete solution. We apply the same method in the analysis of the macroeconomic system. In this chapter we deal with the determination of National Income under the assumption of fixed price of final goods and constant rate of interest in the economy. The theoretical model used in this chapter is based on the theory given by John Maynard Keynes. 4.1 AGGREGATE DEMAND AND ITS COMPONENTS In the chapter on National Income Accounting, we have come across terms like consumption, investment, or the total output of final goods and services in an economy (GDP). These terms have dual connotations. In Chapter 2 they were used in the accounting sense – denoting actual values of these items as measured by the activities within the economy in a certain year. We call these actual or accounting values ex post measures of these items. These terms, however, can be used with a different connotation. Consumption may denote not what people have actually consumed in a given year, but what they 2020-21 54 54 54 54 54 Introductory Macroeconomics had planned to consume during the same period. Similarly, investment can mean the amount a producer plans to add to her inventory. It may be different from what she ends up doing. Suppose the producer plans to add Rs 100 worth goods to her stock by the end of the year. Her planned investment is, therefore, Rs 100 in that year. However, due to an unforeseen upsurge of demand for her goods in the market the volume of her sales exceeds what she had planned to sell and, to meet this extra demand, she has to sell goods worth Rs 30 from her stock. Therefore, at the end of the year, her inventory goes up by Rs (100 – 30) = Rs 70 only. Her planned investment is Rs 100 whereas her actual, or ex post, investment is Rs 70 only. We call the planned values of the variables – consumption, investment or output of final goods – their ex ante measures. In simple words, ex-ante depicts what has been planned, and ex-post depicts what has actually happened. In order to understand the determination of income, we need to know the planned values of different components of aggregate demand. Let us look at these components now. 4.1.1. Consumption The most important determinant of consumption demand is household income. A consumption function describes the relation between consumption and income. The simplest consumption function assumes that consumption changes at a constant rate as income changes. Of course, even if income is zero, some consumption still takes place. Since this level of consumption is independent of income, it is called autonomous consumption. We can describe this function as: C C cY = + (4.1) The above equation is called the consumption function. Here C is the consumption expenditure by households. This consists of two components autonomous consumption and induced consumption (cY ). Autonomous consumption is denoted by C and shows the consumption which is independent of income. If consumption takes place even when income is zero, it is because of autonomous consumption. The induced component of consumption, cY shows the dependence of consumption on income. When income rises by Re 1. induced consumption rises by MPC i.e. c or the marginal propensity to consume. It may be explained as a rate of change of consumption as income changes. C MPC c Y ? = = ? Now, let us look at the value that MPC can take. When income changes, change in consumption ( ) C ? can never exceed the change in income ( Y) ? . The maximum value which c can take is 1. On the other hand consumer may choose not to change consumption even when income has changed. In this case MPC = 0. Generally, MPC lies between 0 and 1 (inclusive of both values). This means that as income increases either 2020-21 55 55 55 55 55 Income Determination the consumers does not increase consumption at all (MPC = 0) or use entire change in income on consumption (MPC = 1) or use part of the change in income for changing consumption (0< MPC<1). Imagine a country Imagenia which has a consumption function described by C=100+0.8Y . This indicates that even when Imagenia does not have any income, its citizens still consume Rs. 100 worth of goods. Imagenia’s autonomous consumption is 100. Its marginal propensity to consume is 0.8. This means that if income goes up by Rs. 100 in Imagenia, consumption will go up by Rs. 80. Let us also look at another dimension of this, savings. Savings is that part of income that is not consumed. In other words, S Y C = - We define the marginal propensity to save (MPS) as the rate of change in savings as income increases. S MPS s Y ? = = ? Since, S Y C = - , ( ) 1 Y C s Y Y C Y Y c ? - = ? ? ? = - ? ? = - Some Definitions Marginal propensity to consume (MPC): it is the change in consumption per unit change in income. It is denoted by c and is equal to C Y ? ? . Marginal propensity to save (MPS): it is the change in savings per unit change in income. It is denoted by s and is equal to 1 c - . It implies that 1 s c + = . Average propensity to consume (APC): it is the consumption per unit of income i.e., C Y . Average propensity to save (APS): it is the savings per unit of income i.e., S Y . 2020-21 56 56 56 56 56 Introductory Macroeconomics 4.1.2. Investment Investment is defined as addition to the stock of physical capital (such as machines, buildings, roads etc., i.e. anything that adds to the future productive capacity of the economy) and changes in the inventory (or the stock of finished goods) of a producer. Note that ‘investment goods’ (such as machines) are also part of the final goods – they are not intermediate goods like raw materials. Machines produced in an economy in a given year are not ‘used up’ to produce other goods but yield their services over a number of years. Investment decisions by producers, such as whether to buy a new machine, depend, to a large extent, on the market rate of interest. However, for simplicity, we assume here that firms plan to invest the same amount every year. We can write the ex ante investment demand as I = I (4.2) where I is a positive constant which represents the autonomous (given or exogenous) investment in the economy in a given year. 4.2 DETERMINATION OF INCOME IN TWO-SECTOR MODEL In an economy without a government, the ex ante aggregate demand for final goods is the sum total of the ex ante consumption expenditure and ex ante investment expenditure on such goods, viz. AD = C + I. Substituting the values of C and I from equations (4.1) and (4.2), aggregate demand for final goods can be written as AD = C + I + c.Y If the final goods market is in equilibrium this can be written as Y = C + I + c.Y where Y is the ex ante, or planned, ouput of final goods. This equation can be further simplified by adding up the two autonomous terms, C and I , making it Y = A + c.Y (4.3) where A = C + I is the total autonomous expenditure in the economy. In reality, these two components of autonomous expenditure behave in different ways. C , representing subsistence consumption level of an economy, remains more or less stable over time. However , I has been observed to undergo periodic fluctuations. A word of caution is in order. The term Y on the left hand side of equation (4.3) represents the ex ante output or the planned supply of final goods. On the other hand, the expression on the right hand side denotes ex ante or planned aggregate demand for final goods in the economy. Ex ante supply is equal to ex ante demand only when the final goods market, and hence the economy, is in equilibrium. Equation (4.3) should not, therefore, be confused with the accounting identity of Chapter 2, which states that the ex post value of total output must always be equal to the sum total of ex post consumption and ex post investment in the economy. If ex ante demand for final goods falls short of the output of final goods that the producers have planned to produce in a given year, equation (4.3) will not hold. Stocks will be piling up in the warehouses which we may consider as unintended accumulation of inventories. It should be noted that inventories or stocks refers to that part of output produced which is not sold and therefore remains with the firm. Change in inventory is called 2020-21 57 57 57 57 57 Income Determination inventory investment. It can be negative as well as positive: if there is a rise in inventory, it is positive inventory investment, while a depletion of inventory is negative inventory investment. The inventory investment can take place due to two reasons: (i) the firm decides to keep some stocks for various reasons (this is called planned inventory investment) (ii) the sales differ from the planned level of sales, in which case the firm has to add to/run down existing inventories (this is called unplanned inventory investment). Thus even though planned Y is greater than planned C + I, actual Y will be equal to actual C + I, with the extra output showing up as unintended accumulation of inventories in the ex post I on the right hand side of the accounting identity. At this point, we can introduce a government in this economy. The major economic activities of the government that affect the aggregate demand for final goods and services can be summarized by the fiscal variables Tax (T) and Government Expenditure (G), both autonomous to our analysis. Government, through its expenditure G on final goods and services, adds to the aggregate demand like other firms and households. On the other hand, taxes imposed by the government take a part of the income away from the household, whose disposable income, therefore, becomes Y d = Y – T. Households spend only a fraction of this disposable income for consumption purpose. Hence, equation (4.3) has to be modified in the following way to incorporate the government Y = C + I + G + c (Y – T ) Note that G – c.T , like C or I , just adds to the autonomous term A . It does not significantly change the analysis in any qualitative way. We shall, for the sake of simplicity, ignore the government sector for the rest of this chapter. Observe also, that without the government imposing indirect taxes and subsidies, the total value of final goods and services produced in the economy, GDP, becomes identically equal to the National Income. Henceforth, throughout the rest of the chapter, we shall refer to Y as GDP or National Income interchangeably. 4.3 DETERMINATION OF EQUILIBRIUM INCOME IN THE SHORT RUN You would recall that in microeconomic theory when we analyse the equilibrium of demand and supply in a single market, the demand and supply curves simultaneously determine the equilibrium price and the equilibrium quantity. In macroeconomic theory we proceed in two steps: at the first stage, we work out a macroeconomic equilibrium taking the price level as fixed. At the second stage, we allow the price level to vary and again, analyse macroeconomic equilibrium. What is the justification for taking the price level as fixed? Two reasons can be put forward: (i) at the first stage, we are assuming an economy with unused resources: machineries, buildings and labours. In such a situation, the law of diminishing returns will not apply; hence additional output can be produced without increasing marginal cost. Accordingly, price level does not vary even if the quantity produced changes (ii) this is just a simplifying assumption which will be changed later. 4.3.1 Macroeconomic Equilibrium with Price Level Fixed (A) Graphical Method As already explained, the consumers demand can be expressed by the equation C C cY = + 2020-21Read More

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