Background: Increased levels of obesity have been reported for people with intellectual disability based on data mostly gathered in high income countries. Likewise few studies internationally have focussed on underweight in this population. Method: Data on obesity and underweight were analysed from nearly 86,500 youth and adults with intellectual…

Because of their efficiency and ability to keep many other factors constant, twin studies have a special appeal for investigators. Just as with any teaching dataset, a "matched-sets" dataset used to illustrate a statistical model should be compelling, still relevant, and valid. Indeed, such a "model dataset" should meet the…