Deciding whether a time series that appears nonstationary is in fact fractionally integrated or subject to structural change is a diffcult task. However, various tests have recently been introduced for distinguishing long memory from level shifts and nonlinearity. In this paper, three testing...

College graduates tend to earn more than non-graduates but it is difficult to ascertain how much of this empirical association between wages and college degree is due to the causal effect of a college degree and how much is due to unobserved factors that influence both wages and education (e.g....