Application of Smoothing Methods to Dynamic Energy Expenditure Measurements in Children

• Activity Number: 566
• Type: Contributed
• Date/Time: Wednesday, August 1, 2012 : 2:00 PM to 3:50 PM
• Sponsor: Section on Nonparametric Statistics
• Author(s): Jong Soo Lee*+ and Nancy Butte and Issa Zakeri
• Companies: University of Delaware and Baylor College of Medicine and Drexel University
• Keywords: Smoothing splines ; Confidence bands ; Pediatrics

Abstract

Understanding patterns of energy expenditure of children during discrete periods of time is of interest in pediatrics and scientific community in general. Smoothing or filtering algorithms may be applied to reduce the signal-to-noise ratio in a dataset and thereby capture the important patterns in the energy expenditure data. Smoothing removes instrumentation noise or insignificant rapid phenomenon. Room respiration calorimeters were used to measure minute-by-minute energy expenditure in 109 children, ages 5-18. In order to visualize and interpret patterns, a smoothing spline technique was applied to define the minute-by-minute energy expenditure data during sleep. We show that the method of smoothing splines gives satisfactory results. Moreover, we introduce a technique for constructing confidence bands that is more practical than the usual confidence intervals. We conclude that this smoothing splines method efficiently captured the subtle patterns of energy expenditure during sleep and has potential application for other biological phenomenon.