Comment on "An excess of massive stars in the local 30 Doradus starburst"

Schneider et al. (Reports, 5 January 2018, p. 69) used an ad hoc statistical method in their calculation of the stellar initial mass function. Adopting an improved approach, we reanalyze their data and determine a power-law exponent of . Alternative assumptions regarding dataset completeness and the star formation history model can shift the inferred exponent to and, respectively. They estimate the ages and masses of individual stars with the BONNSAI Bayesian code (3), then obtain an overall mass distribution by effectively adding together the posterior probability density functions of individual stars. There is no statistical meaning to a distribution obtained in this way, which does not represent the posterior probability density function on the mass distribution. Hierarchical Bayesian inference provides the statistically justified solution to this problem (4).