In multiple regressions, explanatory variables with simple correlation coe¢ cients with the dependent variable below 0.1 in absolute value (such as aid with economic growth) may have very large and statistically significant estimated parameters which are unfortunately "outliers driven" and spurious. This is obtained by including another regressor which is highly correlated with the initial regressor, such as a lag, a square or interaction terms of this regressor. The analysis is applied on the "Botswana outliers driven" Burnside and Dollar [2000] article which found that aid had an effect on growth only for countries achieving "good" macroeconomic policies.JEL classi…cation: C12, O19, P45

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Abstract This paper studies how the assignment of patents as collateral determines the savings of …rms and magni…es the e¤ect of innovative rents on investment in research and development (R&D). We analyse the behaviour of innovative …rms that face random and lumpy investment opportunities in R&D. High growth rates of innovations, possibly higher than the real rate of interest, may be achieved despite …nancial constraints. There is an optimal level of publicly funded policy by the patent and trademark o¢ ce that minimizes the legal uncertainty surrounding patents as collateral and maximizes the growth rate of innovations. Terms of use: Documents in EconStor may

No abstract

International audienceThis paper studies how credit rationing affects endogenous growth when capital and debt are related to the firm´s internal net worth, taken as collateral. The accumulation of firm´s net worth determines the growth rate of capital and the growth rate of the economy. The relation between growth and interest rate is then negative without requiring convex adjustment costs on investment

For static panel data models that include endogenous time-invariant variables correlated with individual e¤ects, exogenous averages over time of time-varying variables can be internal instruments. To pretest their exogeneity, we …rst estimate a random e¤ects model that includes all averages over time of time-varying variables (Mundlak, 1978;Krishnakumar, 2006). Internal instruments are then selected if their parameter is statistically di¤erent from zero (Mundlak, 1978;Hausman and Taylor, 1981). Finally, we estimate a Hausman-Taylor (1981) model using these internal instruments. We then evaluate the biases of currently used alternative estimators in a Monte-Carlo simulation: repeated between, ordinary least squares, two-stage restricted between, Oaxaca-Geisler estimator, …xed e¤ect vector decomposition, and random e¤ects (restricted generalized least squares).

This algorithm extends Ljungqvist and Sargent (2012) algorithm of Stackelberg dynamic game to the case of dynamic stochastic general equilibrium models including exogenous forcing variables. It is based Anderson, Hansen, McGrattan, Sargent (1996) discounted augmented linear quadratic regulator. It adds an intermediate step in solving a Sylvester equation. Forward-looking variables are also optimally anchored on forcing variables. This simple algorithm calls for already programmed routines for Ricatti, Sylvester and Inverse matrix in Matlab and Scilab. A final step using a change of basis vector computes a vector auto regressive representation including Ramsey optimal policy rule function of lagged observable variables, when the exogenous forcing variables are not observable.JEL classification numbers: C61, C62, C73, E47, E52, E61, E63.

This paper compares different implementations of monetary policy in a new-Keynesian setting. We can show that a shift from Ramsey optimal policy under short-term commitment (based on a negative feedback mechanism) to a Taylor rule (based on a positive feedback mechanism) corresponds to a Hopf bifurcation with opposite policy advice and a change of the dynamic properties. This bifurcation occurs because of the ad hoc assumption that interest rate is a forward-looking variable when policy targets (inflation and output gap) are forward-looking variables in the new-Keynesian theory.JEL classification numbers: C61, C62, E43, E44, E47, E52, E58.

Macroeconomic theories of the 1980s faced accelerated depreciation when not sudden death. By contrast with econometrics and microeconomics and despite massive progress in access to data and the use of statistical softwares, macroeconomic theory appears not to be a cumulative science so far. When attempts are done to settle controversies by "nature" (testing the theories), they are designed to fail due to Gresham's law of selecting theories based on too many parameters, which are weakly or non-identified when testing them. Two examples are provided, one in growth theory and testing convergence, one in business cycles theory and testing inflation persistence.JEL classification numbers: B22, B23, B41, C52, E31, O41, O47.