BACKGROUND Scientifically sound methods for investigating dietary consumption patterns from self-serve salad bars are needed to inform school policies and programs. OBJECTIVE To examine the reliability and validity of digital imagery for determining starting portions and plate waste of self-serve salad bar vegetables (which have variable starting portions) compared with manual weights. DESIGN/METHODS In a laboratory setting, 30 mock salads with 73 vegetables were made, and consumption was simulated. Each component (initial and removed portion) was weighed; photographs of weighed reference portions and pre- and post-consumption mock salads were taken. Seven trained independent raters visually assessed images to estimate starting portions to the nearest ¼ cup and percentage consumed in 20% increments. These values were converted to grams for comparison with weighed values. STATISTICAL ANALYSES Intraclass correlations between weighed and digital imagery-assessed portions and plate waste were used to assess interrater reliability and validity. Pearson's correlations between weights and digital imagery assessments were also examined. Paired samples t tests were used to evaluate mean differences (in grams) between digital imagery-assessed portions and measured weights. RESULTS Interrater reliabilities were excellent for starting portions and plate waste with digital imagery. For accuracy, intraclass correlations were moderate, with lower accuracy for determining starting portions of leafy greens compared with other vegetables. However, accuracy of digital imagery-assessed plate waste was excellent. Digital imagery assessments were not significantly different from measured weights for estimating overall vegetable starting portions or waste; however, digital imagery assessments slightly underestimated starting portions (by 3.5 g) and waste (by 2.1 g) of leafy greens. CONCLUSIONS This investigation provides preliminary support for use of digital imagery in estimating starting portions and plate waste from school salad bars. Results might inform methods used in empirical investigations of dietary intake in schools with self-serve salad bars.

中文翻译：

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用于测量学校沙拉吧的起始部分和盘子废料的数字图像方法的可靠性和有效性

背景 需要科学合理的方法来调查自助沙拉吧的饮食消费模式，以告知学校政策和计划。目的 与手动称重相比，检查数字图像用于确定自助沙拉吧蔬菜（具有可变起始部分）的起始部分和盘子浪费的可靠性和有效性。设计/方法 在实验室环境中，制作了 30 份含有 73 种蔬菜的模拟沙拉，并模拟了食用量。称重每个组件（初始部分和移除部分）；拍摄了称重的参考部分和食用前和食用后模拟沙拉的照片。七名训练有素的独立评分员目视评估图像，以估计最接近的 1/4 杯的起始部分和以 20% 的增量消耗的百分比。这些值被转换为克以与称重值进行比较。统计分析 称重和数字图像评估部分与板废料之间的类内相关性用于评估评估者之间的可靠性和有效性。还检查了 Pearson 的权重和数字图像评估之间的相关性。配对样本 t 检验用于评估数字图像评估部分和测量重量之间的平均差异（以克为单位）。结果 评分者间的可靠性对于使用数字图像的起始部分和印版浪费而言非常出色。就准确性而言，类内相关性中等，与其他蔬菜相比，确定绿叶蔬菜起始部分的准确性较低。然而，数字图像评估的废版的准确性非常好。数字图像评估与用于估计整体蔬菜起始部分或浪费的测量重量没有显着差异；然而，数字图像评估略微低估了绿叶蔬菜的起始部分（3.5 克）和浪费（2.1 克）。结论 这项调查为使用数字图像估计学校沙拉吧的起始份量和盘子浪费提供了初步支持。结果可能会为提供自助沙拉吧的学校膳食摄入量实证调查中使用的方法提供信息。结论 这项调查为使用数字图像估计学校沙拉吧的起始份量和盘子浪费提供了初步支持。结果可能会为提供自助沙拉吧的学校膳食摄入量的实证调查提供信息。结论 这项调查为使用数字图像估计学校沙拉吧的起始份量和盘子浪费提供了初步支持。结果可能会为提供自助沙拉吧的学校膳食摄入量实证调查中使用的方法提供信息。