Self-determination motivation theory in R: The software package SDT

This paper presents the technical details of the software package SDT in the R computing and graphics environment, implementing a convex quadratic program that was recently proposed in the literature on self-determination theory of human motivation. Three main features are addressed, with their accompanying code for computation in R: first, the application of the quadratic program and corresponding code for the analysis of the extent of motivation internalization or externalization; second, for exploring the simplex structure assumption of motivation; and third, for adjusting the confounded scoring protocol, called the self-determination or relative autonomy index, to account for the mixture of internal motivation and external motivation. We describe the functions of the R package SDT. The computations are demonstrated with example data accompanying the package, so researchers can run the methodology on their own datasets.