Author's response to reviews Title:Influences of socioeconomic factors on childhood and adolescent overweight by gender in Korea: cross-sectional analysis of nationally representative sample Authors:

Author's response to reviews: see over Dear editor-in-chief, Thank you for the kind and thoughtful opinion. It makes our paper more interesting and meaningful. We tried to do our best to revise the paper upon referee's advices. We addressed the comments in a revised manuscript. Here below is the detail explanation giving a point-by-point response to the concerns. Subject: MS: 5422170161117657-Influences of socioeconomic factors on childhood and adolescent obesity by sex in Korea: cross-sectional analysis of nationally representative sample Referee 1: Jinming Yu Major Compulsory Revisions 1. Methods part. The authors stated that the study subjects were selected using stratified probability proportional to size method from 12 cities. How the stratification was conducted? Specifically, how each subject was selected? Did the author select a whole school, grade, or class? Ł The study population ranged in age from 10 to 18 years and was selected from 12 cities in Korean provinces except for Jeju Island and included a total sample of 10,156 children and adolescents. Ł The study has used stratified cluster sampling that can represent the population. It was conducted like below; 1) Stratum: Allocation target sample population by proportion of the number of students by stratification from 12 cities 2) Decided the number of schools according to allocated sampling number 3) Cluster: selecting allocated school per stratified cities (Sampling with Probabilities Proportional to Size, which is applied the number of students per school) 4) Choosing one grade from selected school 5) Sampling: random selection of one class among number of class of selected grade by random number and 6) Face to face interview of all students of the selected class 2. Methods part. How the weight and height of study subjects were measured? Was it self-reported? If it was self-reported, did the author assess the validity of the self-reported weight and height before? Ł It was measured by self-reported. There was no validity test. We added this as a limitation of this study. However, the trained interviewers asked structured questionnaires to get more accuracy answers. 3. Methods part. The authors did not state which variables were considered as confounders and how they were measured. Ł We added on statistical analysis part of the method section about which variables were considered as confounders like below; " Logistic regression was used to calculate the odds ratio and 95% confidence interval, while adjusting for possible confounders. We considered gender, education, region, parent's …