USING OVERLAPPING GENERATIONS MODEL WITH MONEY FIND OPTIMAL SAVING FUNCTION:
The overlapping generations (OLG) model, is one of the dominating frameworks of analysis, in the study of macroeconomic dynamics and economic growth. OLG model was inspired by Irving Fisher's monograph 'The Theory of Interest' was first formulated in 1947, in the context of a pure-exchange economy by Maurice Allais and later more rigorously by Paul Samuelson in 1958. It contains agents who are born at different dates and have finite lifetimes, even though the economy goes on forever. This induces a natural heterogeneity across individuals at a point in time as well as nontrivial life-cycle considerations for a given individual across time. These features of the model can also generate differences from models where there is a finite set of time periods and agents, or from models where there is an infinite number of time periods, but agents live forever. A closely related feature of the model is that it has a role for fiat money. The OLG model is a framework of study for: Life-cycle behavior, implications of allocated resources across generations, such as Social Security, on the income per capita in the long-run or to determine economic growth, and the factors that trigger the fertility transition.
Basic assumptions of the OLG model:
Problem with the basic OLG model is that there is no store of value except money, but this can sometimes be fixed up by adding productive capital. This pure-exchange OLG model was augmented with the introduction of an aggregate neoclassical production by Peter Diamond. The OLG economy under this model is characterized by multiple steady-state equilibria, which can affect the long-run level of income per capita. The economy will have the following characteristics:
In an overlapping generations model with money, where t- 1,2,3,.... So, every period t, a generation of two-period lived agents are born. They are endowed with e units of the consumption good, when young, and e units of the consumption good, when old. Assume that e > e° >0. The consumption good is perishable. The initial old also have a quantity M of intrinsically valueless fiat money. Trading takes place as described in class, i.e., old agents may purchase goods from young agents, using their money. Let st be the amount of savings, erpressed in units of the good, which a young agent will save in period t, using money. There is no other store of ualue. Let π,-R/P-1 be the inflation from period t-1 to t, where P is the price in units of money for one unit of the consumption good in order to calculate the optimal savings function.
Here we will allocate the initial generation with an amount of outside money m. There is outside money: money, that is, on net, an asset of the private economy. This includes fiat currency issued by the government and inside money (such as bank deposits) is both an asset as well as a liability of the private sector (in the case of deposits an asset of the deposit holder, a liability to the bank). If m 0, then m can be interpreted as fiat money. If m < 0, one should envision the initial old people having borrowed from some institution (outside the model) and m is the amount to be repaid.
Preferences of individuals are representable by: ut(c) = U(c t t ) + βU(c t t+1)
Preferences of the initial old generation is representable by: u0(c) = U(c 0 1)
We shall assume that U is strictly increasing and twice continuously differential.
An allocation c 0 1 , f(c t t , c t t+1 )g ∞ t=1 is Pareto
optimal if it is feasible and if there is no other feasible
allocation cˆ 1 0 , f(cˆ t t , cˆ t t+1 )g ∞ t=1 such that: ut(cˆ t
t , cˆ t t+1 ) ut(c t t , c t t+1 ) for all t 1 u0(cˆ 0 1 ) u0(c 0
1 ) with strict inequality for at least one t 0.
In the presence of money (m 0), we will take
money to be the numeraire. This is important since we can only
normalize the price of one commodity to 1. With money, no further
normalization is admissible. Let pt be the price of one unit of the
consumption good at period t. Given that the period utility
function U is strictly increasing, the budget constraints hold with
equality.
Summing the budget constraints of agents: c t t+1 + c t+1 t+1 + s t+1 t+1 = e t t+1 + e t+1 t+1 + (1 + rt+1)s t.
By resource balance: s t+1 t+1 = (1 + rt+1)s t
Doing the same manipulations for generation 0 and 1: s 1 1 = (1 + r1)m
By repeated substitution: s t t = Πt τ=1 (1 + rτ)m
Therefore, the amount of saving (in terms of the period t consumption good) has to equal the value of the outside supply of assets, Πt τ=1 (1 + rτ)m.
This condition should appear in the definition of equilibrium. By Walrasílaw, however, either the asset market or the good market equilibrium condition is redundant. So
For rt+1 > 1, we combine both budget constraints into: c t t + 1 1 + rt+1 c t t+1 = e t t + 1 1 + rt+1 e t t+1
Divide by pt > 0: c t t + pt+1 pt c t t+1 = e t t + pt+1 pt e t t+1
Divide initial old generation by p1 > 0 to obtain: c 0 1 e 0 1 + m
Hence, it looks that 1 + rt+1 = pt pt+1 must play a key role.
From the equivalence, the return on the asset equals: 1 + rt+1 = pt pt+1 = 1 1 + πt+1 (1 + rt+1)(1 + πt+1) = 1 rt+1 πt+1 where πt+1 is the ináation rate from period t to t + 1.
Using: p1 = 1 1 + r1 pt+1 = pt 1 + rt+1 with repeated substitution delivers: pt = 1 Πt τ=1 (1 + rτ) ) Πt τ=1 (1 + rτ) = 1 pt
Now, note that we argued before that s t t = Πt τ=1 (1 + rτ)m Hence: s t t = m pt
The total money supply is no longer constant: in = 1 it is $; in = 2 it is $ + $ = 2 · $; in = 3 it is 2 · $ + $ = 3 · $; and, in general, in period , it is · $. In view of this, the money market equilibrium condition in period holds that · $ = () · %() · − (). Thus, %() = · $ () · − () and %( + 1) = ( + 1) · $ ( + 1) · − ( + 1) . Using the relationship ( + 1) = (1 + ) · (), %() %( + 1) = · $ () · − () ( + 1) · $ (1 + ) · () · − ( + 1) = (1 + ) · + 1 · − ( + 1) − () .
You can think about this last condition both as:
1 An equilibrium condition.
2 A money demand function.
Problem 2. Consider an overlapping generations model with money, where t = 1,2,3,.... So, every period...
Problem 2. Consider an overlapping generations model with money, where t = 1,2,3,.... So, every period t, a generation of two-period lived agents are born. Their preferences are . They are endowed with ey units of the consumption good, when young, and e° units of the consumption good, when old. Assume that ey > eo > 0. The consumption good is perishable The initial old also have a quantity M of intrinsically valueless fiat money. Trading takes place as described...
Problem 2. Consider an overlapping generations model with money, where t = 1,2,3,.... So, every period t, a generation of two-period lived agents are born. Their preferences are . They are endowed with ey units of the consumption good, when young, and e° units of the consumption good, when old. Assume that ey > eo > 0. The consumption good is perishable The initial old also have a quantity M of intrinsically valueless fiat money. Trading takes place as described in class, i.e.,...
Problem 2. Consider an overlapping generations model with money, where t = 1,2,3,.... So, every period t, a generation of two-period lived agents are born. Their preferences are . They are endowed with ey units of the consumption good, when young, and e° units of the consumption good, when old. Assume that ey > eo > 0. The consumption good is perishable The initial old also have a quantity M of intrinsically valueless fiat money. Trading takes place as described in class, i.e.,...
QUESTION 2 (Total: 15 marks) Consider an overlapping generations model as discussed in Chapter 7. In which people live for 3 periods. People receive endowment y only when they are young and zero endowments during other times. The population growth rate is n>1. People can hold physical capital which yields return after two periods: each unit of capital generates X units of consumption goods after two periods and then capital disintegrates. Note it is impossible for an individual to observe...
2.1. Consider an economy with a constant population of N 100. Each person is endowed with y-20 units of the consumption good when young and nothing when old. a. What is the equation for the feasible set of this economy? Portray the feasible set on a graph. With arbitrarily drawn indifference curves, illustrate the stationary combination of c1 and C2 that maximizes the utility of future generations b. Now look at a monetary equilibrium. Write down equations that represent the...
2.1. Consider an economy with a constant population of N 100. Each person is endowed with y-20 units of the consumption good when young and nothing when old. a. What is the equation for the feasible set of this economy? Portray the feasible set on a graph. With arbitrarily drawn indifference curves, illustrate the stationary combination of c1 and C2 that maximizes the utility of future generations b. Now look at a monetary equilibrium. Write down equations that represent the...
Problem 1. Consider the problem of an agent at date t, who marimizes the utility function に0 subject to a sequence of budget constraint, where B is the discount factor, c+k is consumption in period t+ k and 1/η is the intertemporal elasticity of substitution Let P+k be the price level prevailing at date t+k, i.e. Pt+k Dollar buy 1 unit of the consumption good in period t +k. Among the various assets that the agent can trade at date...
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Problem 1. Consider the problem of an agent at date t, who marimizes the utility function に0 subject to a sequence of budget constraint, where B is the discount factor, c+k is consumption in period t+ k and 1/η is the intertemporal elasticity of substitution Let P+k be the price level prevailing at date t+k, i.e. Pt+k Dollar buy 1 unit of the consumption good in period t +k. Among the various assets that the agent can trade...
Problem 1. Consider the problem of an agent at date t, who marimizes the utility function に0 subject to a sequence of budget constraint, where B is the discount factor, c+k is consumption in period t+ k and 1/η is the intertemporal elasticity of substitution Let P+k be the price level prevailing at date t+k, i.e. Pt+k Dollar buy 1 unit of the consumption good in period t +k. Among the various assets that the agent can trade at date...
1. Many companies use a incoming shipments of parts, raw materials, and so on. In the electronics industry, component parts are commonly shipped from suppliers in large lots. Inspection of a sample of n components can be viewed as the n trials of a binomial experimem. The outcome for each component tested (trialD will be that the component is classified as good or defective defective components in the lot do not exceed 1 %. Suppose a random sample of fiver...