Statistical Analysis
We computed a weighted average of the body-mass-index val- ues for each subject during each childhood age interval and in adulthood (at 21 through 29 years of age). The weighting was based on the time between the available values. Values closely spaced in time received less weight than widely spaced values, so that the average would not be unduly influenced by the values clustered close together in time. The formula used for the average was as follows: