Choosing the Optimal Set of Instruments from Large Instrument Sets

It is well known that instrumental variables (IV) estimation is sensitive to the choice of instruments both in small samples and asymptotically. Recently, Donald and Newey (2001) suggested a simple method for choosing the instrument set. The method involves minimising the approximate mean square error (MSE) of a given IV estimator where the MSE is obtained using refined asymptotic theory. An issue with the work of Donald and Newey (2001) is the fact that when considering large sets of valid instruments, it is not clear how to order the instruments in order to choose which ones ought to be included in the estimation. The present paper provides a possible solution to the problem using nonstandard optimisation algorithms. The properties of the algorithms are discussed. A Monte Carlo study illustrates the potential of the new method.Instrumental Variables, MSE, Simulated Annealing, Genetic Algorithms

The advantage of transparency in monetary policy instruments

Monetary policy instruments differ in tightness - how closely they are linked to inflation - and transparency - how easily they can be monitored. Tightness is always desirable in a monetary policy instrument; when is transparency? When a government cannot commit to follow a given policy. We apply this argument to a classic question: Is the exchange rate or the money growth rate the better monetary policy instrument? We show that if the instruments are equally tight and a government cannot commit to a policy, then the exchange rate's greater transparency gives it an advantage as a monetary policy instrument.Monetary policy ; Foreign exchange rates ; Inflation (Finance) - Mathematical models

Market access and minimum quality standards

In this paper we analyze market access blocking properties of a Minimum Quality Standard (MQS). For an importing country that imports a high and low quality good, the welfare maximizing optimal MQS limits market access only to the high quality firm. This result is further confirmed for a uniform MQS imposed by a high quality producing country that imports a low quality good. The optimal MQS in this case always blocks entry to the low quality foreign firm. We then propose a Flexible Quality Standard (FQS). Under a FQS a good is taxed if it does not meet the standard. Otherwise, imports are exempt from the tariff. Both firms stay in the market under a FQS and discriminatory import tariff. Total welfare in this case is greater than under free trade and under the optimal MQS (for a pure importing country). With uniform conditional tariffs also both firms stay in the market, however, the welfare obtained is greater than under free trade and lower than under a MQS

Unbiased Instrumental Variables Estimation Under Known First-Stage Sign

We derive mean-unbiased estimators for the structural parameter in instrumental variables models with a single endogenous regressor where the sign of one or more first stage coefficients is known. In the case with a single instrument, there is a unique non-randomized unbiased estimator based on the reduced-form and first-stage regression estimates. For cases with multiple instruments we propose a class of unbiased estimators and show that an estimator within this class is efficient when the instruments are strong. We show numerically that unbiasedness does not come at a cost of increased dispersion in models with a single instrument: in this case the unbiased estimator is less dispersed than the 2SLS estimator. Our finite-sample results apply to normal models with known variance for the reduced-form errors, and imply analogous results under weak instrument asymptotics with an unknown error distribution

The advantage of transparent instruments of monetary policy

A classic question in international economics is whether it is better to use the exchange rate or the money growth rate as the instrument of monetary policy. A common argument is that the exchange rate has a natural advantage since exchange rates provide signals of policymakers? actions that are easier to monitor than those provided by money growth rates. We formalize this argument in a simple model in which the government chooses which instrument it will use to target inflation. In it, the exchange rate is more transparent than the money growth rate in that the exchange rate is easier for the public to monitor. We find that the greater transparency of the exchange rate regime makes it easier to provide the central bank with incentives to pursue good policies and hence gives this regime a natural advantage over the money regime.Monetary policy - Mathematical models ; Foreign exchange rates ; Inflation (Finance) - Mathematical models

Environmental Policy à la Carte: Letting Firms Choose their Regulation

Environmental policy often has to be devised under informational constraints, like uncertainty and asymmetric information. We consider an environmental policy that aims at reducing the welfare losses caused by asymmetric information while being sufficiently simple for implementation. In this policy, firms can choose between being regulated with an emission tax or a permit market. This serves as a screening device; the firms reveal private information by choosing an instrument. We show that such a menu of policy options improves upon conventional environmental policy. Furthermore, the optimal policy is simple and thus easily implementable. The approach is also theoretically interesting, because the simultaneous use of price- and quantity-based instruments induces an asymmetry into the pricesversus- quantities decision compared to Weitzman’s criterion. Especially, there can be an optimal pooling equilibrium where all firms choose the tax, but it is never optimal that all firms participate in permit trading.Environmental Policy, Asymmetric Information, Screening, Uncertainty, Prices-versus-Quantities

Emissions Taxes and Abatement Regulation Under Uncertainty

We consider environmental regulation in a context where firms invest in abatement technology under conditions of uncertainty about subsequent abatement cost, but can subsequently adjust output in the light of true marginal abatement cost. Where an emissions tax is the only available instrument, policy faces a trade-off between the incentive to invest in abatement technology and efficiency in subsequent output decisions. More efficient outcomes can be achieved by supplementing the emissions tax with direct regulation of abatement technology, or by combining the tax with an abatement technology investment subsidy. We compare the properties of these alternative instrument combinations