Wermuth, Nanny; Cox, D. R. - In: Biometrika 95 (2008) 1, pp. 17-33
Undetected confounding may severely distort the effect of an explanatory variable on a response variable, as defined by a stepwise data-generating process. The best known type of distortion, which we call direct confounding, arises from an unobserved explanatory variable common to a response and...