controlled for there is a further pervasive source of bias, namely the co-movement of firm employment and firm wages. In a simple … aggregate or firm level) to firm's employment and wages cause downward bias in OLS regression estimates of RTT. We show that the … between 3.5% and 4.5% of wages at 20 years of tenure — over 80% (50%) of the estimated RTT level itself. The results extend to …