Modeling Dynamic Pies: Recent Advances in the Modeling of Dynamic Compositional Outcomes - Guy D. Whitten, December 10|11, 2020

What do proportions of government budgets allocated to particular policy areas, support for political parties, and shares of total income for quartiles of a national population have in common? They are examples of compositional variables that evolve in important ways over time. In each case, we can express the outcome of interest as a set of relative proportions such that a gain in one area must be offset by a loss in another area or areas. In the Dynamic Pie Project, we are developing modeling strategies to allow researchers to test theories about the determinants of compositions as they evolve over time with a heavy emphasis on producing intuitive graphics to convey the results from such analyses. This approach allows researchers to better model the zero sum context of tradeoff relationships that are pervasive in the real world.