This project is IEU research, linked with Laura Howe's MRC fellowship and the IEU stats theme. Analysis will be carried out by Sam Brilleman with supervision from Laura Howe and Kate Tilling.

Aim: to evaluate the use of Bayesian individual knot point models for modelling growth across childhood and adolescence and estimating age of puberty onset, and to compare these models with alternative approaches such as SITAR

Exposure: age

Outcome: height and weight

Confounding variables: gender

Project justification: Self-reported measures of pubertal status can be inaccurate and there is often lots of missing data due to participant embarrassment. Height-based indices of pubertal development offer an attractive alternative that may be both more accurate and result in less missing data. In this project, we will use all available height and weight data to estimate trajectories of growth across childhood and adolescence, using models that allow person-specific ages at which the rate of growth changes. The idea is that the timing of these knowpoints may be informative about pubertal growth spurts. The models will be compared with other approaches to identifying pubertal growth spurts from growth trajectories, e.g. superimposition by translation and rotation (SITAR), a method developed by Tim Cole.