Effectiveness of home based early intervention on children’s BMI at age 2: randomised controlled trial

BMJ 2013; 346 doi: (Published 14 March 2013) Cite this as: BMJ 2013;346:f1650

The authors of this Research paper (BMJ 2012;344:e3732, doi:10.1136/bmj.e3732) have alerted us to an error in the paragraph “Sample size.” The second sentence should have read: “To have 80% power to detect a difference in mean BMI of 0.38 [not “0.25”] units between the groups at age 2 at the two sided 5% significance level, we needed a sample size of 252 per group.” The incorrectly published value of 0.25 is, in fact, the calculation for the BMI z score (SD 1.0). BMI z scores were compiled (reported at but not stated in the published paper as BMI was identified as the best measure of change in adiposity. In addition, the data collection was all at 24 months; therefore an adjustment of age (with BMI z score) became unnecessary. This correction has no effect on the results.


Cite this as: BMJ 2013;346:f1650

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