adace - Estimator of the Adherer Average Causal Effect
Estimate the causal treatment effect for subjects that can
adhere to one or both of the treatments. Given longitudinal
data with missing observations, consistent causal effects are
calculated. Unobserved potential outcomes are estimated through
direct integration as described in: Qu et al., (2019)
<doi:10.1080/19466315.2019.1700157> and Zhang et. al., (2021)
<doi:10.1080/19466315.2021.1891965>.