ECON6023 Macroeconomics SEMESTER 1 EXAMINATIONS 2019-20
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ECON6023W1
SEMESTER 1 EXAMINATIONS 2019-20
ECON6023 Macroeconomics
Section A
A1 (25 points) Consider a two period (t=0,1) version of the neoclassical
growth model with the choice of labour input:
max ln(c0 ) - Bh0 + β (ln(c1 ) - Bh1 )
c0 ,c1 ,k1 ,k2 ,h0 ,h1
s.t.:
c0 + k1 = k0(α)h0(1) -α ,
c1 + k2 = k 1(α)h 1(1) -α .
where β e (0, 1), B > 0, c0 , c1 , k1 , k2 , h0 , h1 > 0, α e (0, 1) and k0 is given. All variables have the usual meaning.
(a) Formulate the optimization problem in the last period, t = 1. What is/are the state variable(s) in period t = 1? Find the optimal decision rules for c1 , k2 and h1 , and the value function
V1 . [12.5]
(b) Formulate the optimization problem in period t = 0 recursively, in terms of the value function in the last period, V1 . Solve for the optimal decision rules for c0 , k1 and h0 . [12.5]
A2 (25 points) Consider the Markov chain with 3 possible states, X =
{e1 , e2 , e3 }, and the following transition matrix:
P = ┌ ┐
'0.25 0.25 0.5'
(a) Compute the following probability:
Prob(et+2 = e2 let = e1 )
[7]
(b) Find the transitory state(s) and the ergodic set(s) of this Markov
chain.
(c) Define the stationary distribution π of the Markov chain.
[5]
[5]
(d) Use the definition in (c) to find the stationary distribution of
this Markov chain.
[8]
Section B
Consider an economy populated by a representative household that lives forever. Time is discrete. The household solves:
o
max βt [u (ct ) + v (1 - ht )] ,
{c≠,h≠,i≠,k≠+1,b≠+1} t=0
subject to
pt bt+1 + ct + it = rt (1 - τk,t )kt + (1 - τw,t )wt ht + bt ,
kt+1 = (1 - δ)kt + it ,
kt+1 > 0,
and
bt+1 > b.
bt+1 is government debt which the government must pay back to the household in period t + 1. This asset is traded in period t at price pt . b < 0 is a lower bound on bonds held by the household:
this lower bound avoids Ponzi schemes and is loose enough to not bind in equilibrium.
The initial level of government debt is zero: b0 = 0. The initial level of capital is positive: k0 > 0. All other variables have the usual interpretation.
In each period, tax revenues and government debt are used by the government to finance some exogenously given and constant gov- ernment spending G > 0. Perfectly competitive firms solve each period
max ┌Af (kt(d), ht(d)) - rt kt(d) - wt h┐t(d) ,
k,h
where kd and hd denote capital and labour demand. A > 0 is a productivity parameter. Preferences and production function f have
the usual neoclassical assumptions. β and δ e (0, 1), and agents have rational expectations.
(a) List the assumptions on preferences that ensure a concave prob-
lem for the household.
(b) Write down the problem of a benevolent planner.
(c) Find the first order conditions of a benevolent planner.
(d) Find the first order conditions for the representative household and firm. [5]
(e) Consider the competitive equilibrium under the following as- sumptions on the fiscal policy: bt+1 = τk,t = 0 for all t, and all government spending financed through the tax on labour
τw,t . Show whether the competitive equilibrium is efficient in the sense that it attains the allocation that solves the planner’s problem. [10]
(f) Suppose that the government is free to choose all policy in- struments τk,t , τw,t , bt+1. Explain whether and how would you deviate from the policy in the previous subquestion in order to maximize the objective function of the household. [10]
2022-01-22