Do Wages Rise with Job Seniority?

Many previous studies have found a strong positive effect of job seniority (tenure) on wages. This paper re-examines the evidence using a simple instrumental variables scheme to deal with the fact that tenure is likely to be related to unobserved individual and job characteristics that affect the wage. We use the variation of tenure over a given job match as the principal instrumental variable for tenure. The variation in tenure over the job is uncorrelated by construction with the fixed individual and job match specific components of the error term of the wage equation. Our main finding is that the partial effect of tenure on wages is small, and that general labour market experience and job shopping account for most wage growth over a career. The strong cross section relationship between tenure and wages is due primarily to heterogeneity bias.