Financial Crises in DSGE Models: The IMF’s MAPMOD

July 18, 2014

By Jaromir Benes, Michael Kumhof and Douglas Laxton

Financial Crises in DSGE Models: A Prototype Model

Financial Crises in DSGE Models: Selected Applications of MAPMOD

These two papers present MAPMOD, a new IMF model designed to study vulnerabilities associated with excessive credit expansions, and to support macroprudential policy analysis. In MAPMOD, bank loans create purchasing power that facilitates adjustments in the real economy. But excessively large and risky loans can impair balance sheets and sow the seeds of a financial crisis. Banks respond to losses through higher spreads and rapid credit cutbacks, with adverse effects for the real economy. These features allow the model to capture the basic facts of financial cycles. The first paper shows the theoretical structure, the second studies the simulation properties of MAPMOD. (This abstract is a merge of the abstracts of the two papers)

These papers provide an interesting look at the kind of models policy institutions devise nowadays to study the economy. What is particularly interesting here is that the model is flexible enough to integrate some unexpected behavior of the economy in the sense of a shock or friction that has not happened yet. If there is no history to draw from, theory needs to come to the rescue, and this can only happen with some serious structural modeling. Here, we have a nice demonstration of that.

Leverage Restrictions in a Business Cycle Model

July 11, 2014

By Lawrence Christiano and Daisuke Ikeda

We modify an otherwise standard medium-sized DSGE model, in order to study the macroeconomic effects of placing leverage restrictions on financial intermediaries. The financial intermediaries (‘bankers’) in the model must exert effort in order to earn high returns for their creditors. An agency problem arises because banker effort is not observable to creditors. The consequence of this agency problem is that leverage restrictions on banks generate a very substantial welfare gain in steady state. We discuss the economics of this gain. As a way of testing the model, we explore its implications for the dynamic effects of shocks.

This paper highlights how special the financial sector is and how putting (particular) restrictions on it can have significant positive impact. In this case, it all boils down to whether it is observable whether we can see how well the banker selects and monitors loans. As the banker use the funds of others, he is not getting the full returns from his efforts and does not try hard enough. And imagine if there where also some other perverse incentives in the model, like limited liability or a bonus pay system that would encourage investing in excessively risky projects.

Endogenous Wage Indexation and Aggregate Shocks

July 9, 2014

By: Julio Carrillo, Gert Peersman and Joris Wauters

Wage indexation practices have changed. Evidence on the U.S. for instance suggests that wages were heavily indexed to past inflation during the Great Inflation but not during the Great Moderation. However, most DSGE models assume fixed indexation parameters in wage setting, which might not be structural in the sense of Lucas (1976). This paper presents a New-Keynesian model in which workers, by maximizing their welfare, set their wage indexation rule in response to aggregate shocks and monetary policy. We find that workers index their wages to past inflation when technology and permanent inflation-target shocks drive output fluctuations; when aggregate demand shocks do, workers index to trend-inflation. In addition, workers’ choices do not coincide with the social planner’s choice, which may explain the observed changes in wage indexation in the post-WWII U.S. data.

Many are unhappy about the way macro models deal with price and wage rigidities, and properly understanding indexation is a neglected part of this reflection. This paper provides an interesting tack at this question. Critical here is the choice set of indexation rules. The relevant part of the paper is here:

[..] in periods in which wages are re-optimised, workers select an indexation rule among two different types: one based on past inflation, and the other one based on the inflation target of the Central Bank (i.e. trend inflation, which may vary). Workers then choose the rule associated with the highest expected utility, given the average length of the labor contract and the regime’s economic characteristics. Similar to Schmitt-Grohe and Uribe (2007), we solve the non-linear model to compute the welfare criterion of workers. The sum of all workers’ decisions determines the degree at which nominal wages are indexed to past inflation on average. We name this level the degree of aggregate indexation in the economy. We implement an algorithm that computes the equilibrium level for aggregate indexation, given the economic regime.

Optimal taxation with home production

July 8, 2014

By Conny Olovsson

Optimal taxes for Europe and the U.S. are derived in a realistically calibrated model in which agents buy consumption goods and services and use home capital and labor to produce household services. The optimal tax rate on services is substantially lower than the tax rate on goods. Specifically, the planner cannot tax home production directly and instead lowers the tax rate on market services to increase the relative price of home production. The optimal tax rate on the return to home capital is strictly positive and the welfare gains from switching to optimal taxes are large.

This paper makes a very simple, but often neglected point. If market services and home produced goods (say, restaurant meals and home-cooked meals) are substitutes, one needs to tax market services less than other goods. The intuition is simple: you want to avoid flight to the home production sector that cannot be taxed. Were they complements, then the taxes should be higher, so as to tax the otherwise untaxable. The paper quantifies all this and shows this is really important, especially once you factor in that households react to the tax environment.

News, Housing Boom-Bust Cycles, and Monetary Policy

June 18, 2014

By Birol Kanik and Wei Xiao

We explore the possibility that a housing market boom-bust cycle may arise when public beliefs are driven by news shocks. News, imperfect and noisy by nature, may generate expectations that are overly optimistic or pessimistic. Over-optimism easily leads to excessive accumulation of housing assets, and creates a housing boom that is not based on fundamentals. When the news is found false or inaccurate, investors revert their actions, and a downturn in the housing market follows. By altering agents’ net worth conditions, a housing cycle can have significant repercussions in the aggregate economy. In this paper, we construct a dynamic general equilibrium model that can give rise to a news-driven housing boom-bust cycle, and we consider how monetary policies should respond to it.

What the abstract does not mention is that the news shocks does not pertain directly to the housing market. The mechanism is as follows. Positive news about increase expected future net worth, which raise aggregate demand, include housing. The higher house prices relax borrowing contraints as houses are used as collateral, which amplifies the total effect. We have thus an amplifier running entirely on news.

Fiscal Stimuli in the Form of Job Creation Subsidies

June 16, 2014

By Chun-Hung Kuo and Hiroaki Miyamoto

This paper examines the effects of fiscal stimuli in the form of job creation subsidies in a DSGE model with search frictions in the labor market. We consider two types of job creation subsidies: a subsidy to the cost of posting vacancies and a hiring subsidy. Our model demonstrates that qualitative effects of a vacancy cost subsidy are similar to those of a hiring subsidy. Quantitatively, however, the vacancy cost subsidy is more effective in lowering unemployment than the hiring subsidy. We also compute fiscal multipliers for both traditional increases in government spending and increases in job creation subsidies.

The two stimuli have the same cost to the government, and as the firm is risk-neutral, taking one or the other does not affect directly the value of posting a vacancy. As so often in general equilibrium models, the action is all in the derivatives. A posting subsidy encourages directly firms to post, but to hire only indirectly. A hiring subsidy is more targeted, and thus more effective, and even more so than spending that subsidy in general public expenses, which are of course the least targeted.

The One-Child Policy and Household Savings

June 4, 2014

By Taha Choukhmane, Nicolas Coeurdacier and Keyu Jin

We ask how much the advent of the ‘one child policy’ can explain the sharp rise in China’s household saving rate. In a life-cycle model with endogenous fertility, intergenerational transfers and human capital accumulation, we show a macroeconomic and a microeconomic channel through which restrictions in fertility raise aggregate saving. The macro-channel operates through a shift in the composition of demographics and income across generations. The micro-channel alters saving behaviour and education decisions at the individual level. A main objective is to quantify these various channels in the data. Exploiting the birth of twins as an identification strategy, we provide direct empirical evidence on the micro-channel and show its quantitative relevance in accounting for the rise in the household saving rate since the inception of the policy in 1980. Our quantitative OLG model can explain from a third to at most 60% of the rise in aggregate saving rate; equally important is its implied shift in the level and shape of the age-saving profile consistent with micro-level estimates from the data.

The main mechanism at play in this paper are the transfers from children to parents, whose amount is decreasing in the number of children. Once parents are restricted to one child, they need to compensate with their own savings to obtain the desired level of consumption in retirement. The social convention that children help their parents and social security (rather, its absence) are left untouched to isolate the impact of the child policy. While the latter is big, it may be mitigated or amplified by social and institutional change that accompanied the child policy and may in fact be a consequence of it. A China specialist may weigh in here. It is nevertheless an interesting paper.


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