What is the Optimal Environment for a Postdoctoral Researcher

We examine the research papers produced by postdoctoral researchers in reference to their postdoctoral systems. We find a difference among papers where the target postdoctoral researcher is not the first author. In particular, the number of papers in which the first author belongs to other institutes from the target postdoctoral researchers is quite different. Furthermore, coauthored papers correlate with a difference in the H-index of the postdoctoral researchers. This indicates that collaboration during postdoctoral research may affect the future career of those researchers.