Study design and time frame used in this study. Xudong Liu Xiaorong Wang Sihao Lin Qingkun Song Xiangqian Lao Ignatius Tak-Sun Yu 10.1371/journal.pone.0134627.g001 https://plos.figshare.com/articles/figure/_Study_design_and_time_frame_used_in_this_study_/1499579 <p>FFQ was administrated at the baseline (FFQ1) and one year later (FFQ2) at rural health clinics by trained interviewers with a face-to face approach. Six times 3-day 24-hour recalls (24HRs) surveys were performed between the two FFQs in every two month. The first 24HRs were performed one month later after the FFQ1. Several interviewers visited to participants with local dialect. All participants were asked to recall all foods (including recipes/ingredients of mixed dishes) and drinks that they consumed from the last day (22:00) to next day (22:00) on the 24-hour dietary recall questionnaires in three consecutive days (including two weekdays and one weekend day). The reliability of FFQ was assessed by comparing the dietary pattern scores between FFQ1 and FFQ2. The Validity of the FFQ was assessed by comparing the dietary pattern scores between FFQs and 24HRs.</p> 2015-07-31 03:18:53 food frequency questionnaire ffq 24 HRs.ConclusionThe study Dietary Pattern Method Pearson correlation coefficients principle component factor analysis factor loadings Chinese Rural Population ObjectiveThis study Intraclass correlation coefficients food pattern intraclass correlation coefficient