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Zhang Collaborating in Childhood Obesity Study

Health economist Zhang

Old Dominion University health economist Qi "Harry" Zhang is collaborating with researchers at the Bloomberg School of Public Health at Johns Hopkins University on a $1.6 million project that will try to get to the roots of the childhood obesity epidemic in the United States and find ways to reverse the trend.

The National Institutes of Health (NIH) project, which is titled "Causes and Interventions for Childhood Obesity: Innovative Systems Analysis," extends through June 2014. The grant's principal investigator is Youfa Wang of the Bloomberg School.

Zhang said the innovative analysis borrows from methodology more commonly used by engineers. "Traditionally we use regression-based statistical techniques to analyze data," he explained. "But now we propose to use a system dynamics model, which is traditionally used by engineers, and we apply the method to examine the complicated interactions among components of the food environment. That's quite revolutionary in research methods in the health field."

The researchers are mining data from existing population surveys and health studies for their analysis, which will examine determinants of how many calories children take in versus how many calories they expend. This ratio is called "energy balance" and the researchers are also interested in what they call "energy balance related behaviors" (EBRB).

A specific goal of the work is to examine the relative importance of contextual variables - at home, school or in other environments - as determinants of energy balance. This could involve availability and affordability of healthy foods, sports and recreational offerings, and even parental rules pertaining to television watching or Internet use.

Other aims of the researchers include:

• Determining the key contextual drivers of the childhood obesity epidemic at the population level over the past three decades;

• Using agent-based models to test simple rules to explain individuals' EBRB and obesity risk; and

• Identifying and characterizing several potential intervention/policy strategies.

"We will conduct sensitivity analyses based on various specifications of models," the research team states in the grant proposal. "Our systematic analysis will be conducted using a set of innovative, sophisticated methods including multilevel models, propensity score methods and systems analysis models."

System dynamics is a methodology and mathematical modeling technique for studying complex issues. It is sometimes compared to chaos theory.

The method assumes that the structure of any system - the many circular, interlocking, sometimes time-delayed relationships among its components - is often just as important in determining its behavior as the individual components themselves. It also assumes that there are properties of the whole that cannot be found among the properties of the elements, meaning that in some cases the behavior of the whole cannot be explained in terms of the behavior of the parts.

Zhang, assistant professor of community and environmental health in ODU's College of Health Sciences, has a unique background in studying socioeconomic factors causing obesity and micro-simulation modeling of preventions and interventions. He has worked on another NIH-funded project examining how food prices affect the body weight of low-income population groups in the United States. Zhang and Wang have collaborated on obesity-related studies since 2002.

This article was posted on: March 28, 2011

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