All downhill from the PhD? The typical impact trajectory of U.S. academic careers

Abstract

Within academia, mature researchers tend to be more senior, but do they also tend to write higher impact articles? This article assesses long-term publishing (16+ years) United States (US) researchers, contrasting them with shorter-term publishing researchers (1, 6 or 10 years). A long-term US researcher is operationalised as having a first Scopus-indexed journal article in exactly 2001 and one in 2016-2019, with US main affiliations in their first and last articles. Researchers publishing in large teams (11+ authors) were excluded. The average field and year normalised citation impact of long- and shorter-term US researchers’ journal articles decreases over time relative to the national average, with especially large falls to the last articles published that may be at least partly due to a decline in self-citations. In many cases researchers start by publishing above US average citation impact research and end by publishing below US average citation impact research. Thus, research managers should not assume that senior researchers will usually write the highest impact papers.

Domestic researchers with longer careers generate higher average citation impact but it does not increase over time

“…In Australia, researchers (from three sampled universities) with academic ages 10-29 attract the most citations per publication (Gu & Blackmore, 2017). In the USA (using many of the same methods as the current study, but focusing on long-term researchers authoring at least 5 papers), average citations per publication do not tend to increase over careers, and may tail off towards the end of careers or start to decrease after about a decade (Thelwall, & Fairclough, 2020). For a set of Spanish research council members, younger researchers tended to have higher productivity and citation impact indicators (Costas, van Leeuwen, & Bordons, 2010), but a study of Mexican researchers found almost the opposite (González-Brambila, & Veloso, 2007), either through different methods or international differences.…”

“…Whilst the average numbers of co-authors varies substantially between countries and fields (Thelwall & Maflahi, 2020), the purpose of the threshold is to eliminate the possibility that the results are affected by highly collaborative authors that may have contributed little to their publications. The threshold ten was used in the similar prior study of the USA (Thelwall & Fairclough, 2020), and accounts for less than 3% of articles in all broad fields (Thelwall & Maflahi, 2020). The results will therefore not be relevant for research fields that routinely collaborate more, such as in high value large international health-related studies.…”

“…Career gaps for any reason were ignored because there is no international source of information about these. For the USA, about a fifth of the long-term researchers judged to have a first publication in 2001 in fact had an earlier publication in Scopus from before 1996 (Thelwall & Fairclough, 2020), so the career lengths may be underestimated for a minority of researchers, even if ignoring non-Scopus articles. These rules were used to identify long term researchers (16+ year career publishing in Scopus), medium term researchers (11 year career publishing in Scopus) and short term researchers (6 year career publishing in Scopus).…”

“…Although career trajectories for domestic or national researchers have been investigated for the USA (Thelwall, & Fairclough, 2020), and another study has used different methods with a similar goal for Australia (Gu & Blackmore, 2017) and worldwide career impact changes have been reported as part of a study of productivity (Larivière & Costas, 2016), this is apparently the first internationally comparative longitudinal career impact study using reasonably comprehensive journal article data. The focus is on the Scopus-indexed publications of domestic researchers for pragmatic reasons.…”

Questionnaires mentioned in academic research 1996–2019: Rapid increase but declining citation impact

“…For example, perhaps senior researchers mainly used questionnaires in 1996, needing funding to deliver and administer them, whereas PhD students nowadays are more common users, with the technological skills to use them easily. Seniority does not necessarily associate with increased citation impact (in the USA: Thelwall & Fairclough, 2020a), so seniority alone may not be the reason, but it seems possible that more expensive research methods would be applied more carefully, other factors being equal. For example, web‐based surveys seem to be reported less carefully than offline surveys (Turk et al, 2018).…”