shapleydecomp - Shapley Value Decomposition for Discrete-Time Simulation Models

Attributes changes in the outcomes of a discrete-time simulation model to its input factors using Shapley values (Shapley 1953) <doi:10.1515/9781400881970-018>, which for binary factors coincide with the symmetric standardization of Das Gupta (1993) <https://www2.census.gov/library/publications/1993/demographics/p23-186.pdf>. Any calibrated model can be decomposed by implementing four S3 methods that run the model, summarize its output, and construct counterfactual inputs. Counterfactuals either remove a factor entirely or hold it at its value in a baseline year, and a sequential decomposition attributes each year's policy conditional on the past.