Validity and Calibration of the Youth Activity Profile

Purpose
The purpose of this study was to calibrate and cross-validate the Youth Activity Profile (YAP), a self-report tool designed to capture physical activity (PA) and sedentary behaviors (SB) in youth.
Methods
Eight schools in the Midwest part of the U.S. were involved and a total of 291 participants from grades 4–12 agreed to wear an accelerometer (SWA Armband) and complete the YAP in two separate weeks (5–7 days apart). Individual YAP items capture PA behavior during specific segments of the week and these items were combined with temporally matched estimates of moderate-to-vigorous PA (MVPA) and sedentary time from the SWA to enable calibration. Quantile regression procedures yielded YAP prediction algorithms that estimated MVPA at School, MVPA at Out-of-School, MVPA on Weekend, as well as time spent in SB. The YAP estimates of time spent in MVPA and SB were cross-validated using Pearson product correlations and limits of agreement, as indicative of individual error and, equivalence testing techniques as indicative of group-level error.
Result
Following calibration, the correlations between YAP and SWA estimates of MVPA were low to moderate (rrange = .19 to .58) and individual-level YAP estimates of MVPA ranged from -134.9% to +110.0% of SWA MVPA values. Differences between aggregated YAP and SWA MVPA ranged from -3.4 to 21.7 minutes of MVPA at the group-level and predicted YAP MVPA estimates were within 15%, 20%, and 30%, of values from the SWA for the School, Out-of-School, and Weekend time periods, respectively. Estimates of time spent in SB were highly correlated with each other (r = .75). The individual estimates of SB ranged from -54.0% to +44.0% of SWA sedentary time, and the aggregated group-level estimates differed by 49.7 minutes (within 10% of the SWA aggregated estimates).
Conclusions
This study provides preliminary evidence that the calibration procedures enabled the YAP to provide estimates of MVPA and SB that approximated values from an objective monitor. The YAP provides a simple, low-cost and educationally sound method to accurately estimate children’s MVPA and SB at the group level.

研究目的：本研究旨在对青少年活动量表（Youth Activity Profile, YAP）进行校准与交叉验证，该工具是一款用于采集青少年体力活动（physical activity, PA）与久坐行为（sedentary behaviors, SB）信息的自报告量表。
研究方法：本研究纳入美国中西部地区的8所学校，共计291名4至12年级的参与者自愿佩戴加速度计（SWA Armband），并在间隔5至7天的两个独立周内分别完成YAP问卷。YAP的各条目用于采集一周特定时段内的体力活动行为，将这些条目与来自SWA的、时间匹配的中高强度体力活动（moderate-to-vigorous PA, MVPA）与久坐时长估计值相结合，以完成校准流程。通过分位数回归程序，生成了可分别估算在校中高强度体力活动、校外中高强度体力活动、周末中高强度体力活动以及久坐时长的YAP预测算法。本研究采用皮尔逊积矩相关系数、一致性界限以评估个体层面误差，并采用等效性检验技术以评估群体层面误差，以此对YAP的中高强度体力活动与久坐时长估计值进行交叉验证。
研究结果：校准完成后，YAP与SWA的中高强度体力活动估计值之间的相关性处于低至中等水平（相关系数范围为0.19至0.58）；个体层面的YAP中高强度体力活动估计值与SWA测得值的偏差范围为-134.9%至+110.0%。群体层面的聚合YAP与SWA中高强度体力活动时长差值范围为-3.4至21.7分钟，且在校、校外、周末三个时段的YAP预测中高强度体力活动估计值分别落在SWA测得值的15%、20%与30%区间内。久坐时长的估计值之间具有较高相关性（r=0.75）；个体层面的YAP久坐时长估计值与SWA测得值的偏差范围为-54.0%至+44.0%，群体层面的聚合估计值差值为49.7分钟，且落在SWA聚合估计值的10%区间内。
研究结论：本研究提供了初步证据，表明校准流程可使YAP对中高强度体力活动与久坐时长的估计值接近客观监测设备的测得结果。YAP是一种操作简便、成本低廉且符合教育逻辑的方法，可在群体层面准确估算儿童的中高强度体力活动与久坐时长。