The Phantom Menace of Omitted Variables: A Comment
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 advised to include a relevant control variable on this basis alone, particularly when it is weakly correlated with the variable of interest.
Vance, C. Ph.D. und N. Ritter (2012), The Phantom Menace of Omitted Variables: A Comment. Conflict Management and Peace Science, 29, 2, 233-238