The Possibility of Applying the Vitamin D Brief Food Frequency Questionnaire as a Tool for a Country with No Vitamin D Data in Food Composition Tables.

[ 30 ], the mean difference, limit of agreement (LoA), as well as Bland-Altman index were calculated, after a log transformation applied due to non-parametric distribution, as commonly applied [ 34 ], while a Bland-Altman index of 5% was interpreted as a positive validation [ 35 ] and a Bland-Altman index of 10% was interpreted as a borderline significant [ 36 ], which was assumed a priori [ 37 ], (2) analysis of cross-classification in quartiles: the share of correctly classified and grossly misclassified (classified to the opposite quartiles) individuals were indicated, while at least 50% of correctly classified and, at the same time, less than 10% of grossly misclassified individuals was interpreted as a positive validation [ 38 ]; (3) analysis of the weighted κ statistic: as a method recommended by Cade et al.

also in 11,409 other papers