Super Imposition by Translation and Rotation Growth Curve Analysis R package sitar version 1.5.0 Functions for fitting and plotting SITAR (Super Imposition by Translation And Rotation) growth curve models. SITAR is a shape-invariant model with a regression B-spline mean curve and subject-specific random effects on both the measurement and age scales. The model was first described by Lindstrom (1995) <doi:10.1002/sim.4780141807> and developed as the SITAR method by Cole et al (2010) <doi:10.1093/ije/dyq115>. Software Depends: nlme, R (>= 4.1.0) Imports: dplyr, forcats, ggplot2, glue, graphics, magrittr, methods, purrr, rlang, rsample, splines, splines2, stats, tibble, tidyr Suggests: knitr, rmarkdown Tim Cole <tim.cole@ucl.ac.uk> Comprehensive R Archive Network (CRAN) Tim Cole [cre, aut, cph] (ORCID: <https://orcid.org/0000-0001-5711-8200>) GPL (>= 2) 2025-07-26 application/tgz https://CRAN.R-project.org/package=sitar doi:10.32614/CRAN.package.sitar