Discretizing continuous variables in nutrition and obesity research: a practice that needs to be cut short.

BACKGROUND/OBJECTIVES: Nutrition and obesity researchers often dichotomize or discretize continuous independent variables to conduct an analysis of variance to examine group differences. We describe consequences associated with dichotomizing and discretizing continuous variables using two cross-sectional studies related to nutrition. SUBJECTS/METHODS: Study 1 investigated the effects of health literacy and nutrition knowledge on nutrition label accuracy (n = 612). Study 2 investigated the effects of cognitive restraint and BMI on fruit and vegetable (F/V) intake (n = 586). We compare analytic approaches where continuous independent variables were either discretized/dichotomized or analyzed as continuous variables. RESULTS: In Study 1, dichotomization of health literacy and nutrition knowledge for 2 × 2 ANOVA revealed health literacy had an effect on nutrition label accuracy. Nutrition knowledge has an effect on nutrition label accuracy, but the health literacy by nutrition knowledge interaction was not significant. When analyzed using regression, the nutrition knowledge effect was significant. The simple effect of health literacy was also significant when health literacy equals zero. Finally, the quadratic effect of health literacy was negative and significant. In Study 2, dichotomization and discretization of cognitive restraint and BMI were used for three ANOVAs, which discretized BMI in three ways. For all ANOVAs, the BMI main effect for predicting fruit and vegetable intake was significant, the interaction between BMI and cognitive restraint was non-significant, and cognitive restraint was only significant when both variables were dichotomized. When analyzed using regression, the continuous mean-centered variables, and their interaction each significantly predicted F/V intake. CONCLUSIONS: Dichotomizing continuous independent variables resulted in distortions of effect sizes across studies, an inability to assess the quadratic effect of health literacy, and an inability to detect the moderating effect of BMI. We discourage researchers from dichotomizing and discretizing continuous independent variables and instead use multiple regression to examine relationships between continuous independent and dependent variables.

Eat Well El Paso!: Lessons Learned From a Community-Level Restaurant Initiative to Increase Availability of Healthy Options While Celebrating Local Cuisine.

PURPOSE: Restaurants have the potential to improve nutrition and positively shape social norms. We describe lessons learned and recommended strategies from Eat Well El Paso! (EWEP), a local restaurant initiative. DESIGN: Descriptive case study. SETTING: EWEP partnered with local restaurants from 2012-2017 in El Paso, Texas, along the US/Mexico border. SAMPLE: Our sampling frame included EWEP staff and managers/owners at participating restaurants, of which the majority participated (80% and 85%, respectively). INTERVENTION: EWEP was a local restaurant initiative led by the city public health department. EWEP contracted registered dietitians to assist locally-owned restaurants to increase availability of healthy menu options. MEASURES: Observation, key informant interviews, and document review assessed participation, barriers, and facilitators to restaurant participation and program sustainability. ANALYSIS: Thematic and descriptive analyses. RESULTS: 57% of restaurants completed the full on-boarding process, but long-term retention was low (24% of completers). Restaurant managers/owners perceived value in marketing, nutritional analysis, and menu design. Barriers included scheduling, complexity of restaurant culture, fear of food inspections, restaurant turnover, competing responsibilities, and lack of dedicated funding. CONCLUSION: Although local context and sample size may limit generalizability, lessons learned and recommended strategies are relevant and informative for communities working to increase restaurants' healthy menu options.

Practical Strategies to Improve Your Writing: Lessons Learned From Public Health Practitioners Participating in a Writing Group.

Many public health professionals (researchers and practitioners) do not regularly spend time writing. We often receive no formal training in the practices that lead one to become a productive writer. In addition, many internal (mental/emotional) and external (schedules/distractions) barriers make writing consistently even less appealing and may lead to a cycle of avoidance followed by binge writing. This commentary demonstrates how one writing group became an effective means of providing career and professional development. Each week for 9 months we held a 1-hour writing group meeting designed around a commitment to ground rules, accountability, training opportunities, and feedback. Our experiences suggest that engaging in a writing group can help us develop as writers by allowing us to learn new practices and skills. Adopting new practices like writing regularly for short blocks of time, in turn, led to benefits like reduced anxiety and increased productivity. In the process, we became better writers, reviewers, and mentors. We provide recommendations and resources for groups and individuals who are interested in improving their writing as an essential component of their continuing education and professional development. Whatever your professional role, using a writing group to become a more powerful and productive writer will make you more effective.