Delayed retirement by US academics is responsible for a 20?per cent reduction in the number of new hires among younger scientists, according to a study.

The analysis, published in , concludes that a 1994 federal policy shift eliminating the mandatory retirement age of 70 for all tenured faculty explains about half the growth in their average age.

The study was produced by researchers at Virginia Polytechnic Institute and State University, who warn that efforts to solve the problem of poor employment prospects for new doctoral graduates are overlooking the important role?that retirement policies can play in the situation.

¡°Many focus on this [young] population, trying to invent new positions for them, or modify PhD education to make it a better fit for industry jobs,¡± said a co-author of the report, Navid Ghaffarzadegan, associate professor of industrial and systems engineering at Virginia Tech. ¡°But these are all focusing on symptoms, and not the root causes.¡±

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While conceding that no statistical model is perfect, Dr Ghaffarzadegan said that his study ¨C tying the 1994 policy to a 20?per cent cut in new faculty hires ¨C tried to improve estimates of cause and effect through a complicated system of variables for the number of faculty at different ages.

Drawing on data on academics in science, engineering and health collected in the biennial Survey of Doctoral Recipients, it finds that the average age of surveyed academics stood at 50.3 in 2010, in comparison with an expected average of 48.8 if mandatory retirement ages had not been abolished.

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According to the predictions conducted by Dr Ghaffarzadegan and his co-author Ran Xu, the average age of academics is expected to reach a ¡°steady state¡± of between 50.9 and 51.7 years in 2025.

Dr Ghaffarzadegan said that it was fairly straightforward to recognise that faculty staying in their jobs for another five years or more on average will have significant effects on the ability of younger scientists to replace them.

While saying that?he understood that universities could benefit by keeping older academics,?Dr Ghaffarzadegan expressed hope that his study might contribute to discussions of more productive late-career options, such as ¡°post-tenure¡± mentoring roles, that could help to clear space for younger faculty.

paul.basken@timeshighereducation.com