The age when scientists are most productive pinpointed by a new study

Why is that so? The explanation is complex and doesn’t mean scientists later in their work path shouldn’t be supported, according to the study’s co-author Bruce Weinberg, professor of economics at The Ohio State University.

For their study, the researchers looked at an extensive dataset of 5.6 million biomedical science articles published over a 30-year period from 1980 to 2009, compiled by MEDLINE. The dataset contained detailed information on the authors of the articles.

How was the innovativeness of biomedical scientists measured? The study considered citations — the number of times other scientists mentioned (or “cited”) the study in question within their work. The more a study was mentioned, the more it was regarded as important or relevant. The rich dataset allowed the researchers to compare how often the work of the scientists was cited during different stages of their careers.

If you take an average researcher, a late-career scientific article by them had one-half to two-thirds less frequency of citations than an article published early in their careers.

One key discovery made by Weinberg and his colleagues Matthew Ross of New York University, Joseph Staudt of the U.S. Census Bureau, as well as Gerald Marschke and Huifeng Yu of the University of Albany's Department of Economics, was that the scientists who exhibited the least amount of innovation in their early careers would often leave the field entirely or quit publishing their research (perhaps shifting to work that did not emphasize publishing). On the other hand, the most productive young scientists were more likely to be still producing and publishing research 20 to 30 years later.

In a press release, Weinberg explained that while in their early careers, scientists could demonstrate “a wide range of innovativeness,” as they get older, there was a “selective attrition of the people who are less innovative.” In this way, overall innovation in the biomedical field did not decline over time but “the fact that the least innovative researchers are dropping out when they are relatively young disguises the fact that, for any one person, innovativeness tends to decline over their career.”

Outside of looking at citations as a measure of innovation, the researchers also created additional metrics. These considered the fields that cited the articles, along with qualitative measures such as whether the article contained the latest ideas on the subject and whether it made conclusions based on multiple disciplines. The metrics led the researchers to the same results on declining innovativeness over time.

Other factors may also explain why some scientists either lead the field or publish less over time, with women and minorities being less likely to have the necessary opportunities for funding and progression, proposed Weinberg.

Interesting Engineering (IE) spoke with Bruce Weinberg directly about their study’s findings.

The following conversation has been lightly edited for clarity and flow.

Interesting Engineering: Why is there a decline in innovation among scientists as they go through their careers? 

Professor Bruce Weinberg: Our study is not as focused on explaining the patterns so much as on documenting them. We do analyze the inputs into research – the newness of ideas, for instance – and find that older researchers are less likely to build on the latest, important, new ideas. 

IE: Do the conclusions hold true across different scientific fields, or is there more decline in certain areas?

Weinberg: We focus on biomedicine, so we cannot extrapolate beyond that, but biomedicine is a very large field with very different subfields, including more mathematical fields such as biostatistics. When we break things down within biomedicine, we find that the decline in innovation with age is consistent across almost all subfields, so we believe that our results are likely to apply broadly. I will also note that when others have sought to understand the relationship between age and innovation, they have often viewed fields like biomedicine as likely to peak late because they are more concrete and empirical and less abstract and mathematical, so it is striking that we find that researchers in biomedicine peak early.

IE: Does the fact that the creative peak is earlier in their careers mean we should support younger scientists more?

Weinberg: It does suggest the importance of supporting young researchers, but it is important to be sure to find the best young researchers.

This statement was echoed by Gerald Marschke, who shared in the press release that: “Young scientists tend to be at their peak of creativity, but there is also a big mix with some being much more innovative than others. You may not be supporting the very best researchers."

Read the study “Publish or Perish: Selective Attrition as a Unifying Explanation for Patterns in Innovation over the Career.”

Abstract:

Studying 5.6 million biomedical science articles published over three decades, we reconcile conflicts in a longstanding interdisciplinary literature on scientists’ life-cycle productivity by controlling for selective attrition and distinguishing between research quantity and quality. While research quality declines monotonically over the career, this decline is easily overlooked because higher “ability” authors have longer publishing careers. Our results have implications for broader questions of human capital accumulation over the career and federal research policies that shift funding to early-career researchers – while funding researchers at their most creative, these policies must be undertaken carefully because young researchers are less “able” on average.