The analyses show high internal quality of the parameters derived from the growth curve models based on their associations with observed birth measures, height, BMI and age at menarche. However, some assumptions had to be made to account for random variation associated with the derived parameters. The weighting of the SNP association analyses by the number of measurements per person within the age period in question assumes that the reliability of the growth data has a proportional relationship with the frequency of measurements taken within the age period, and that the measurement accuracy does not depend on the frequency of the measurements taken. Although these seem reasonable assumptions, they are difficult to verify using this data alone. Ideally the analyses would be weighted by the inverse of the variance attached to the phenotypes derived from the growth models. However, the variances for the derived outcomes could not be directly estimated from the models and we used weighting by the number of measurements as a proxy.
