Ben Highton writes:
Failure to take into account ‘strategic retirement’ leads to inflated estimates of the incumbent electoral advantage. The one attempt to address this issue in the context of US House elections implies that much of the supposed incumbency advantage and most of its presumed increase over time are illusory (Cox and Katz, 2002). This paper identifies possible problems with the Cox and Katz (2002) method and develops a new approach based on simulating the counterfactual condition of incumbents standing for re-election rather than retiring. The results show that when the bias induced by strategic retirement is removed, much of the apparent incumbency advantage and its increase over time remain evident.
This makes me happy because it is consistent with our claims here.