Dietary and Physical Activity Behaviors in 2021 and Changes From 2019 to 2021 Among High School Students: A Replication Study

Shannon L. Michael et al. conducted the study “Dietary and Physical Activity Behaviors in 2021 and Changes from 2019 to 2021 Among High School Students” to compare the prevalences of specific dietary and exercise behaviors among high-school students between 2019 and 2021, in order to examine how the COVID-19 pandemic affected these behaviors and to identify disparities in these effects. This replication of the study focuses on exercise behaviors. The study data, drawn from the CDC’s YRBS in 2019 and 2021, had been selected using a three-stage cluster sampling method in which the clusters in the third stage were selected randomly. T-tests were used to compare 2021’s results by race and sex and 2019’s and 2021’s results, and logistic regression to calculate the associations between one of the five behaviors studied (meeting CDC guidelines for both aerobic and muscle-strengthening exercise) and the other four (being physically active ≥1 hour daily 7 days weekly, performing muscle-strengthening exercises ≥ 3 days weekly, attending PE classes all 5 school days, and playing on ≥ 1 sports team). In 2021, boys were more likely than girls to engage in these behaviors, but there was no clear pattern among racial groups. Overall, their prevalences either stayed the same or decreased between 2019 and 2021; decreases also occurred within racial and gender groups. PE class attendance and sports-team membership were associated with meeting CDC exercise guidelines. The authors of the study concluded that healthy exercise habits had declined during the pandemic. Pure Replication: Using the study data and the authors’ statistical methods (t-tests and logistic regression), I reproduced Tables 4 and 5 of the study, which present and compare between 2019 and 2021 the prevalences of five exercise behaviors, and the associations 3 between one of these behaviors and the other four. Most of my replicated results were consistent with those of the study. MEA: I reanalyzed the data using Pearson’s test, which I felt to be a more appropriate technique in context than the t-test, and checked the assumptions of this test and of logistic regression. My replicated results were also mostly consistent with the study’s. TCA: I reapplied Pearson’s test and logistic regression to determine the effects of two pandemic-related variables on the behaviors.