7. RBC Flashcards
What are vector autoregressions?
Ways of summarising the dynamics of macro data where we are interested in obtaining the impulse response functions
What are impulse responses?
They trace out the response of current and future values of each variable to a one unit increase (or a one standard deviation increase, when scale matters) in the current value of one of the VAR errors
What does DSGE stand for?
Dynamic Stochastic General Equilibrium model
What is the simplest DSGE?
RBC
What is the New Keynesian model?
It combines DSGE structure of RBC models with assumptions that depart from classical monetary models. Features include monopolistic competition and nominal rigidities
What is the consequence of nominal rigidities on changes in short term interest rates?
They aren’t matched by one to one changes in expected inflation
How do financial frictions impact shocks?
They amplify them
What are business cycles?
Expansions and contractions that appear at the same time in different economic sectors.
They are periodical but with variable duration.
What should business cycle models be able to answer?
The source of cyclical fluctuations and the shock transmission mechanism
What second moments are we interested in?
Variance - volatility
Covariance, cross correlation - co-movements
Autocorrelation - degree of persistence
What are the two extreme cases of persistence?
-A random walk Px=1, the series never returns to average, a transitory shock produced permanent effects
-White noise Px=0, a transitory shock doesn’t generate any persistence, it isn’t possible to identify cyclical fluctuations due to the shock
How persistent are most macro variables?
Highly persistent
What must be added to the Ramsey model to understand aggregate fluctuations?
-There must be a source of disturbances.
-They are added in the form of fluctuation shocks- technology shocks. -This is known as an RBC model
What is good about the RBC?
It provides a coherent framework that integrates growth and business cycles
Why is the RBC controversial?
Because the only fluctuations are technology shocks?
What is the HP filter?
It is a model free approach to decomposing a time series into its trend and cyclical components
How is the parameter lambda used in the HP filter?
If lambda is zero we only care about fitting and if lambda is infinity the trend value will never change from one period to the next
How do we adjust lambda when the frequency of our data increases?
We increase lambda
How do empirical VARs suggest that price level and output react to an increase in interest rate?
The aggregate price level doesn’t respond much initially (inflection inertia) but then goes down. Output falls initially with a j shaped response and zero LR effect
What are the advantages of micro founded models?
-they are elegant
-they can be used to evaluate welfare effects of alternative policy
-we can do counterfactual experiments with them since their deep parameters are generally robust to Lucas’ critique
Conceptually what does the RBC highlight?
The efficiency of business cycles
The importance of technology shocks as a source of economic fluctuations
The limited role of monetary factors
Roles of money in the economy
- Medium of exchange
- Store of value
- Unit of account
What do we call the RBC model with money introduced?
The MIU model (money in utility)
What is the result of the MIU model?
It is able to generate non trivial effects to monetary shocks
What assumption is required for the MIU model?
We assume nonseperability between money and consumption (strong assumption)
Keynesian features
It combines the DSGE structure characteristic of RBC models with assumptions that depart from those found in classical monetary models
-Monopolistic competition
-Nominal rigidities
What are the three components of the NK model?
-demand side represented by a linear approximation to the representative Euler condition for optimal consumption
-inflation adjustment is derived under the assumption of monopolistic comp yielding the New Keynesian Phillips curve
-monetary policy is represented by a rule for setting the nominal rate of interest
What does the credit view stress?
Stresses the distinct role played by financial assets and liabilities. It also stresses that some borrowers may be more vulnerable to changes in credit conditions than others
What is the key mechanism involved in the financial accelerator?
It involves the link between external finance premium and the net worth of potential borrowers.
With credit market frictions present and asymmetric info, the external finance premium depends inversely on borrowers’ net worth.
How can collateral constraints create financial accelerator effects?
-adjustment of asset prices following contractionary monetary policy
-borrowers are limited in the amount they can borrow by the value of their assets that can serve as collateral
Simplifying assumptions of RBC
-Capital doesn’t depreciate
-Labour is supplied inelastically
-Utility is logarithmic in consumption
-Technology shocks effect society’s ability to produce goods
In the RBC what do we get when we combine the first two FOCs?
The Euler equation for consumption
What does the Euler equation say in words?
At the margin consumers are indifferent between consuming one unit today and saving it for the future
What is the intuition of the transversality condition?
Consumers don’t accumulate capital up to infinity
What is the zero lower bound and how does it relate to the NK model?
The zero lower bound is the idea that policy rates can only go as lower as zero. This is ignored in the basic NK model. This has ramifications for the effects of other shocks, including fiscal policy shocks
What is the forward guidance puzzle?
It is the idea that effects of a temporary 1% increase in the policy rate 100 years from now is predicted in the basic NK model to be the same as if the increase took place today
What is the HANK model?
Heterogeneous Agent New Keynesian model. It assumes there are idiosyncratic shocks to households labour productivity and hence wages. This causes households to have different marginal propensities to consume
How do low interest rates affect the asset price channel?
Low interest rates increase asset prices. High asset prices increase wealth for consumers and they condone more this shifts AD and inflation and output increase
When do firms use networth as collateral for loans?
When there is asymmetric info
How can the credit channel lead to output shifts?
Expansionary monetary policy increases with firms networth. The problem of moral hazard and adverse selection gets reduced, lending increases, investment increases further as a shift in the investment demand curve, output increases
Following the financial crisis how did the worsening of financial frictions manifest itself?
Widening credit spreads, causing higher costs of credit for households and businesses and tighter lending standards. The resulting decline in lending meant that both consumption expenditure and investment fell, causing the economy to contract
How did the crisis expose micro prudential supervision?
The crisis proved micro prudential supervision isn’t enough to prevent financial crises because the problems of one financial institution can harm others that are otherwise healthy
What is micro prudential supervision?
Focusing on safety and soundness of individual financial institutions
What is macroprudential supervision?
Focusing on the safety and soundness of the financial system as a whole
Which aspects of the crisis in particular does the NK model not display?
The amplification effect attributed to the role of credit supply in the monetary transmission, since it is based on the assumption that the Modigliani- Miller theorem holds and there are no credit market imperfections
Who are the agents in the NK model?
-Households
-Final good firms
-Intermediate good firms
-Government
What do households do in the NK model?
-make consumption and labour supply decisions
-demand money and bonds
What do final good firms do in the NK model?
-produce homogeneous final goods Yt
-use intermediate goods Yjt to produce the final good
What do intermediate good firms do in the NK model?
-use labour to produce intermediate goods Yjt
-over each of these goods they have monopoly power
-demand labour
-can set price of good Yj
What does the government do in the NK model?
Runs monetary policy
In the households maximisation problem what variables do they choose in order to maximise the equation? NK model
Consumption Ct, labour Lt, money Mt, nominal bonds Bt
What does Eo denote in the household maximisation problem? NK model
Denotes the expectation operator conditional on time 0 info
In the NK model what does Ft denote?
Lump sum dividends received from ownership of intermediate good firms
What are total goods given by in the NK model?
The CES aggregator of the different quantities of intermediate goods produced
How are the returns of the production function distributed in the NK model?
Production function has constant returns to scale
Characteristics of intermediate goods firms in NK model
Monopolistically competitive firms
Each firm faces downward sloping demand for its product
It uses labour to produce output according to the following technology Yjt= AtLjt
Calvo pricing
Each producer chooses her own price Pjt
He can reset his price only when given the chance to do so, which occurs with prob 1- theta in each period
What are the constraints of the intermediate goods firms in the NK model?
Production constraint
Demand curve
Prices can only be adjusted with prob 1- theta
How do intermediate goods firms pick the optimal price when given an option to change price in the NK model?
The optimal price is a weighted average of current and expected future nominal marginal costs. Weights depend on expected demand in the future, and how quickly the form discounts profits