Steenhuis I H, Brug J, van Assema P, Imbos T
University of Limburg, Maastricht, The Netherlands.
Nutr Health. 1996;10(4):331-9. doi: 10.1177/026010609601000404.
The objective of the study was to develop and validate a 21-item nutrition knowledge test to measure people's knowledge of the fat content of food-products. After pretesting and provisional development, the test was administered twice to study test-retest reliability. Furthermore, various sub-populations with expected differences in nutrition knowledge completed the test in order to study the construct validity of the questionnaire. The subpopulations consisted of lay-people (N = 81), students of human nutrition and dietetics (N = 108), and professional experts (N = 79) on human nutrition. The internal consistency and uni-dimensionality of the test were determined by calculating the KR-20 statistic and the log-likelihood ratio statistic for the Rasch model. Pearson's correlation and gross misclassification between T1 and T2 were calculated to assess the test-retest reliability. Analysis of variance was used to test for differences in mean knowledge scores between subpopulations. Test-retest reliability was found to be sufficient (R = .85). The internal consistency was moderate (KR20 = .68). According to the Rasch model, two items had to be removed from the test before the log-likelihood ratio statistic of the Rasch model indicated that knowledge about the fat content of food products as assessed by the questionnaire is a uni-dimensional construct. The differences in mean knowledge scores between the subpopulations were significant (p < .01) and in the expected direction (experts > students > lay people). It can be concluded that the test is a reliable and valid instrument to measure knowledge about total fat content in food products and that the Rasch model is a comprehensive method to indicate the reliability of nutritional knowledge tests.
该研究的目的是开发并验证一个包含21个条目的营养知识测试，以衡量人们对食品脂肪含量的了解程度。经过预测试和初步开发后，该测试进行了两次施测以研究重测信度。此外，具有预期营养知识差异的不同亚人群完成了该测试，以研究问卷的结构效度。这些亚人群包括普通人群（N = 81）、人类营养与饮食学专业的学生（N = 108）以及人类营养领域的专业专家（N = 79）。通过计算KR - 20统计量和Rasch模型的对数似然比统计量来确定测试的内部一致性和单维度性。计算T1和T2之间的Pearson相关性和总体错误分类，以评估重测信度。使用方差分析来检验亚人群之间平均知识得分的差异。发现重测信度足够（R = 0.85）。内部一致性为中等（KR20 = 0.68）。根据Rasch模型，在Rasch模型的对数似然比统计量表明问卷所评估的食品脂肪含量知识是一个单维度结构之前，必须从测试中删除两个条目。亚人群之间平均知识得分的差异显著（p < 0.01）且符合预期方向（专家>学生>普通人群）。可以得出结论，该测试是一种可靠且有效的工具，可用于测量食品中总脂肪含量的知识，并且Rasch模型是一种全面的方法，可用于表明营养知识测试的信度。
