This note demonstrates that in applied regression analysis, the variance of a coefficient of interest may decrease from the inclusion of a control variable, contrasting with Clarke’s assertion (2005, 2009) that the variance can only increase or stay the same. Practitioners may thus be well...

This note demonstrates that in applied regression analysis, the variance of a coefficient of interest may decrease from the inclusion of a control variable, contrasting with Clarke’s assertion (2005, 2009) that the variance can only increase or stay the same. Practitioners may thus be...

In this article, I address whether the inclusion of control variables in the hopes of getting an unbiased estimate of the residual variance is a good reason for the inclusion of control variables. I conclude that the inclusion of an additional control variable is unlikely to decrease the...

Scholars often assume that the danger posed by omitted variable bias can be ameliorated by the inclusion of large numbers of relevant control variables. However, there is nothing in the mathematics of regression analysis that supports this conclusion. This paper goes beyond textbook treatments...

The gravity model of trade states that the volume of trade between two countries is proportional to the product of the sizes of the two countries and the inverse of the distance between them. The gravity model, however, was initially suggested for other types of social interactions, and it also...

If terror attacks from groups of one country are followed by similar attacks on the same target from groups of other similar countries, then this could be the consequence of contagion. However, just because one terror incident follows another does not necessarily imply that one is caused by the...