Click here to access the paper on the journal's web site.
Click here for supplemental diagnostic plots related to the linear mixed effects and REEM tree model fits to the software transactions data.
An R package to fit the RE-EM tree is available at CRAN. The current version of the package is 0.90.4, and any earlier versions should be updated or replaced.
Note that a function is also available to implement conditional inference-based trees to longitudinal data; such trees have the property of being unbiased in their selection of splitting variables. See this page for more details.