Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Friedman (1992) argues that regressing cross-country income changes on their final levels can be informative about sigma-convergence (the tendency for the dispersion of income levels to narrow) whereas a similar regression on initial levels of income cannot be. In this note we show that Bliss's (1999) dismissal of this argument is in error. Copyright 2000 by Oxford University Press.