SITAR
SITAR (SuperImposition by Translation And Rotation) is a growth curve model that summarises a whole population of growth trajectories with a single mean curve, and describes each individual with just three parameters that transform that curve: size shifts it up or down, timing shifts it earlier or later, and intensity stretches or compresses its timescale. Fitted as a nonlinear mixed effects model, SITAR can explain up to 99% of the variance in pubertal growth.
See how it works
Watch how each of the three SITAR random effects transforms the population mean growth curve (dark). Then use the sliders to build your own individual’s curve.
Interactive chart: a mean growth curve with a pubertal spurt. The size, timing and velocity sliders below transform it into an individual's growth curve.
The mean growth curve for the population.
Learn more
The full explanatory guide is in preparation. In the meantime, see the sitar R package and our software page for tools to fit SITAR models to your own data.