Finally, to examine possible threshold and nonlinear relationships that might
cut across current overweight and obese
cut points, locally weighted regression techniques were used to generate lines of best fit for the relationships between
BMI z scores and PedsQL total, summary, and subscale scores that differed significantly by weight category; P <.05 was considered significant.
Using
cut - off
points derived from internationally collected data,
BMI values can be used to indicate the proportion of children who are underweight, normal weight, overweight and obese.