Scientists’ research portfolio diversification: full diversification, single and multiple specialization. (a) Log-odds as function of (binary) social relatedness and (standardized) knowledge relatedness, accounting for multiple control variables, for the single specialization specification (i). (b) Estimated coefficient for social relatedness conditional on knowledge relatedness, and distribution of knowledge relatedness (on top, similarity color coded as in Fig. 3c, for the single specialization specification (i)). (c,d) Same as (a) and (b) for the multiple specialization specification (ii).