This paper revisits the issue of estimating the returns to schooling within a framework that allows multiple unobserved skills with potentially time-varying prices where both skills and prices are possibly correlated with schooling. A common approach to addressing the problem of ability bias...

We propose estimators of the memory parameter of a time series that are robust to a wide variety of random level shift processes, deterministic level shifts and deterministic time trends. The estimators are simple trimmed versions of the popular log-periodogram regression estimator that employ...