Pseudo market timing and predictive regressions

"A number of studies claim that aggregate managerial decision variables, such as aggregate equity issuance, have power to predict stock or bond market returns. Recent research argues that these results may be driven by an aggregate time-series version of Schultz's (2003) pseudo market timing bias. We use standard simulation techniques to estimate the size of the aggregate pseudo market timing bias for a variety of predictive regressions based on managerial decision variables. We find that the bias can explain only about one percent of the predictive power of the equity share in new issues, and that it is also much too small to overturn prior inferences about the predictive power of corporate investment plans, insider trading, dividend initiations, or the maturity of corporate debt issues"--National Bureau of Economic Research web site.