There is a widespread belief among economists that adding additional variables to a regression model causes higher standard errors. This note shows that, in general, this belief is unfounded and that the impact of adding variables on coefficients' standard errors is unclear. The concept of...

Leamer first pointed out that a regression model is valid only if all of the assumptions under which it is constructed are valid. In particular, this means that all of relevant regressors which are determinants must be included. In practice, applied econometricians assume that whatever model...

There is a widespread belief among economists that adding additional variables to a regression model causes higher standard errors. This note shows that, in general, this belief is unfounded and that the impact of adding variables on coefficients’ standard errors is unclear. The concept of...

The paper deals with forecasting of spot prices in bulk shipping using simultaneous equations models (SEMs) during the present economic crisis, emphasizing the importance of such models in empirical applied economics and for decision-makers. The SEMs predictive performance on the spot market is...

The paper deals with forecasting of spot prices in bulk shipping using simultaneous equations models (SEMs) during the present economic crisis, emphasizing the importance of such models in empirical applied economics and for decision-makers. The SEMs predictive performance on the spot market is...

The paper deals with forecasting of spot prices in bulk shipping using simultaneous equations models (SEMs) during the present economic crisis, emphasizing the importance of such models in empirical applied economics and for decision-makers. The SEMs predictive performance on the spot market is...

The fundamental problem of external validity is not to generalize from one experiment, so much as to experimentally test generalizable theories. That is, theories that explain the systematic variation of causal effects across contexts. Here we show how the graphical language of causal diagrams...

The fundamental problem of external validity is not to generalize from one experiment, so much as to experimentally test generalizable theories. That is, theories that explain the systematic variation of causal effects across contexts. Here we show how th