Task management supported by analytics has enhanced effectiveness through automated population splitting for generating models that predict task associated outcomes. Subpopulations are automatically analyzed for adequate sample size and selectively recombined based on characteristics of the subpopulations, such as to combine homogeneous subpopulations or to optimize a subpopulation characteristic. As an example, outbound calling campaign models are generated for time periods by splitting a sample population into time period subpopulations and combining subpopulation time periods having inadequate sample size so that combined subpopulations have a minimized total time period or greater similarity relative to other subpopulations.