Department of Exercise, Nutrition & Health Sciences, University of Bristol, Tyndall Avenue, Bristol, BS8 1TP, UK.
Int J Behav Nutr Phys Act. 2009 Mar 31;6:20. doi: 10.1186/1479-5868-6-20.
Theoretically, increased levels of physical activity self-efficacy (PASE) should lead to increased physical activity, but few studies have reported this effect among youth. This failure may be at least partially attributable to measurement limitations. In this study, Item Response Modeling (IRM) was used to develop new physical activity and sedentary behavior change self-efficacy scales. The validity of the new scales was compared with accelerometer assessments of physical activity and sedentary behavior.
New PASE and sedentary behavior change (TV viewing, computer video game use, and telephone use) self-efficacy items were developed. The scales were completed by 714, 6th grade students in seven US cities. A limited number of participants (83) also wore an accelerometer for five days and provided at least 3 full days of complete data. The new scales were analyzed using Classical Test Theory (CTT) and IRM; a reduced set of items was produced with IRM and correlated with accelerometer counts per minute and minutes of sedentary, light and moderate to vigorous activity per day after school.
The PASE items discriminated between high and low levels of PASE. Full and reduced scales were weakly correlated (r = 0.18) with accelerometer counts per minute after school for boys, with comparable associations for girls. Weaker correlations were observed between PASE and minutes of moderate to vigorous activity (r = 0.09 - 0.11). The uni-dimensionality of the sedentary scales was established by both exploratory factor analysis and the fit of items to the underlying variable and reliability was assessed across the length of the underlying variable with some limitations. The reduced sedentary behavior scales had poor reliability. The full scales were moderately correlated with light intensity physical activity after school (r = 0.17 to 0.33) and sedentary behavior (r = -0.29 to -0.12) among the boys, but not for girls.
New physical activity and sedentary behavior change self-efficacy scales have fewer items than classical test theory derived alternatives and have reasonable validity for boys, but more work is needed to develop comparable scales for girls. Fitting the items to a underlying variable could be useful in tailoring interventions to this scale.
从理论上讲，较高的身体活动自我效能感（PASE）水平应该会导致身体活动增加，但很少有研究报告在年轻人中存在这种效果。这种失败至少部分归因于测量的局限性。在这项研究中，使用项目反应建模（IRM）来开发新的身体活动和久坐行为改变自我效能感量表。新量表的有效性与身体活动和久坐行为的加速度计评估进行了比较。
开发了新的 PASE 和久坐行为改变（电视观看、电脑视频游戏使用和电话使用）自我效能感项目。来自美国七个城市的 714 名六年级学生完成了这些量表。一小部分参与者（83 人）还佩戴了加速度计五天，并提供了至少三天完整的完整数据。使用经典测试理论（CTT）和 IRM 分析新量表；使用 IRM 生成一个简化的项目集，并与放学后每分钟的加速度计计数和每天久坐、轻度和中高强度活动的分钟数相关联。
PASE 项目区分了 PASE 的高低水平。全量表和简化量表与男孩放学后每分钟的加速度计计数之间存在弱相关性（r = 0.18），女孩的相关性相当。PASE 与中高强度活动的分钟数之间的相关性较弱（r = 0.09-0.11）。通过探索性因子分析和项目对潜在变量的拟合以及在潜在变量长度上的可靠性评估，确立了久坐量表的单维性，但存在一些局限性。简化的久坐行为量表的可靠性较差。全量表与男孩放学后的轻度体力活动（r = 0.17 至 0.33）和久坐行为（r = -0.29 至 -0.12）中度相关，但女孩没有。
新的身体活动和久坐行为改变自我效能感量表的项目数少于经典测试理论衍生的替代量表，并且对男孩具有合理的有效性，但需要进一步开发针对女孩的可比量表。将项目拟合到潜在变量中可能有助于针对该量表进行干预。
