  We approach productivity in science in a longitudinal fashion: We track
careers over time, up to 40 years. We first allocate scientists to decile-based
publishing productivity classes, from the bottom 10% to the top 10%. Then, we
seek patterns of mobility between the classes in two career stages: assistant
professorship and associate professorship. Our findings confirm that radically
changing publishing productivity levels (upward or downward) almost never
happens. Scientists with a very weak past track record in publications emerge
as having marginal chances of becoming scientists with a very strong future
track record across all science, technology, engineering, mathematics, and
medicine (STEMM) fields. Hence, our research shows a long-term character of
careers in science, with publishing productivity during the apprenticeship
period of assistant professorship heavily influencing productivity during the
more independent period of associate professorship. We use individual-level
microdata on academic careers (from a national registry of scientists) and
individual-level metadata on publications (from the Scopus raw dataset). Polish
associate professors tend to be stuck in their productivity classes for years:
High performers tend to remain high performers, and low performers tend to
remain low performers over their careers. Logistic regression analysis
powerfully supports our two-dimensional results. We examine all internationally
visible Polish associate professors in five fields of science in STEMM fields
(N = 4,165 with N art = 71,841 articles).
