This paper considers factor estimation from heterogenous data, where some of the variables are noisy and only weakly informative for the factors. To identify the irrelevant variables, we search for zero rows in the loadings matrix of the factor model. To sharply separate these irrelevant...

This paper argues that mainstream economics does not follow the positivist research tradition it (often implicitly) claims to follow and expresses some serious doubt that econometrics in particular can make economics a hard science. Mathematical rigour and sophisticated statisti-cal techniques...