This papers builds on previous work in which we try to characterize the diversity of roles researchers play in their work life. Specifically, this paper relates to the type of contributions they conduct when collaborating with other researchers on the production of scientific outputs. For this, we use a dataset which combines contribution statements along with bibliometric data on researchers’ academic age and position in the author order. With this, we explain how age and author order affect the probability of researchers on conducting each of the contribution statements using multinomial-responsive regression modelling. In this paper we focus solely on papers authored by up to 4 researchers. These models are not good for predicting contributorship. Something which as already noted elsewhere. Still, they do show that differences on contributions are not only explained by author order but also by seniority. Next, we plan to continue expanding these analyses to papers conducted by larger teams, as well as to researchers working in areas other than biomedical fields.