README.txt file gives a brief explanation of all the files in the Supplementary Material folder. 

The original data used in this paper were restricted-use data that cannot be made public. Thus, all the data files provided in the supplementary material folder are based on the public version. In the public version, for location type ("Locale"), small, midsize, and large cities were all coded as "city" to protect students' identities; also, the variable "region" was kept confidential. Thus, in the data files provided in the supplementary folder, the "location type" was categorized in the same way as the public version; the region was simulated as a random variable. The simulated data also contains roughly 1500 more observations for each outcome as it was based on the publicly released data (part of the data cleaning in the paper was based on variables and coding only in the restricted use data). Because of these changes "region" (which is randomly assigned in the simulated data) will likely not be significant and there will be changes to the "locale".  These changes and larger sample size result in some substantially different p-values for the various other variables but the partial eta squared are similar in most cases between the simulated data provided and the restricted data used in the paper. For the trees, the larger sample size in the simulated data will sometimes result in additional splits at the lower levels, but the overall structure is substantially similar. For information on receiving access to NCES restricted use data, see https://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2013060.

Data Files: 
X1MathSMFinal.sav #used to run ANCOVA analysis and regression tree analysis for the outcome variable-Fall Math Performance.
X2MathSMFinal.sav #used to run ANCOVA analysis and regression tree analysis for the outcome variables-Spring Math Performance and Math Gain.
X1ReadingSMFinal.sav #used to run ANCOVA analysis and regression tree analysis for the outcome variable-Fall Reading Performance.
X2ReadingSMFinal.sav #used to run ANCOVA analysis and regression tree analysis for the outcome variable-Spring Math Performance and Math Gain.

Code Files:
SPSS Syntax.sps #used to run ANCOVA analyses.
SPSS Modeler Commands for Regression Trees.txt. #contains menu-driven commands to build regression trees in SPSS Modeler.

Supplemental Files for the Manuscript:
Supplemental Tree File #provided an expanded overview of CRT method.
Supplemental Tables and Figures File.pdf #provided additional ANCOVA result tables and regression tree figures for the outcome variables--Spring Math Performance, Math Gain, Fall Reading Performance, Spring Math Performance, Math Gain.
