the preprint describing this paper is available at:
Lorenzo-Luaces, L., Wiedemann, M., Huibers, M., & Lemmens, L. H. (2020, October 2). A permutation test to probe the statistical significance of sudden gain frequency: An application to patterns of change in cognitive and interpersonal therapy for depression. https://doi.org/10.31234/osf.io/jbzw3
the code is available as supplemental material here