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NORC News

Kroeger recipient of OPE Postdoctoral Scholars Award that supplements NIH grant

October 5, 2015

Cynthia M. Kroeger, PhD, post-doctoral fellow in the Nutrition Obesity Research Center (NORC) and Office of Energetics, is the recipient of an Office of Postdoctoral Education (OPE) Postdoctoral Scholars Award—established by the OPE as a financial incentive to encourage scholars to apply for individual fellowships—which combines with a National Institutes of Health (NIH) F32 grant to help to fund her study into “Research-Reporting Fidelity within Dietary Weight-Loss Supplement Scientific Literature.”

“Research reporting fidelity” refers to the ability to reliably analyze and present data in scientific papers, talks, and press releases, so that the data and methods used are described without artifice or exaggeration, while also offering sufficient detail for other scientists to judge and replicate the methods. Although a current health research concern involves the prospect of compromised research-reporting fidelity in many domains, the literature on dietary weight-loss supplements may contain some of the most pervasive and egregious breaches. In a nation where the majority of its citizens struggle with obesity, dietary weight-loss supplements are a popularly employed resource; therefore, any gap between evidence-based science and conclusions drawn about weight-loss supplements is of concern to biomedical research as well as to public health, given not only the number of studies conducted on these supplements but also the number of persons taking them.

This proposed study by Dr. Kroeger—under the mentorship of David B. Allison, PhD, distinguished professor and director of the NORC and Office of Energetics—will focus on a phenomenon commonly referred to as "p-hacking," which is defined as “reanalyzing data using various tests until a p-value below the nominal alpha level is obtained” thus inflating the chances of obtaining false positive results, and common errors in the calculation of effect sizes in meta-analytic research. Main study aims include determining the prevalence of p-hacking within weight-loss supplement literature with unprecedented magnitude, speed, and efficiency by combining sophisticated statistical methods, such as multiple imputation and double sampling, as well as by employing the use of crowdsourcing; establishing the frequency of effect size estimation errors that occur within peer-reviewed meta-analyses conducted on dietary weight-loss supplements, by systematically reviewing meta-analyses conducted on weight-loss supplements; and developing and testing the efficacy of three brief training modules for early career investigators, which are designed to enhance effect-size estimation data reproducibility using weight-loss supplement meta-analyses, by conducting a simple randomized controlled trial.

Dr. Kroeger states, “The methodological advances this proposal aims to foster will enhance the technical capabilities of future researchers who wish to employ the use of multiple imputation, double sampling, and crowdsourcing to investigate questions requiring the extraction of large amounts of detailed information from existing scientific literature. Additionally, the results obtained from this project will help improve the accuracy and reproducibility of dietary weight-loss supplement research, making accurate scientific information more accessible to the novice, the broader scientific community, regulatory agencies, medical decision makers, and for public health to help improve the health and life quality of persons taking, or considering taking, dietary supplements for weight loss.”

Dr. Kroeger’s research interests include how brain and behavior factor into obesity development and treatment, statistics, research methods, research transparency, and reproducibility. At UAB she will receive further training in obesity, statistics, meta-research, and teaching methods. She received NIH funding (F32DK107157) to research two topics of research reporting fidelity, namely p-hacking and effect size estimation errors. She will be evaluating the prevalence of these two issues within published dietary weight loss supplement scientific literature as well as developing and testing training modules for early career investigators, designed to improve effect size estimations and data reproducibility.