MSD NEI VFQ Files

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The Excel programs \'91NEI VFQ-25C MSD person measures.xlsm\'92, \'91NEI VFQ-VF MSD person measures.xlsm\'92, and \'91NEI VFQ-SE MSD person measures.xlsm\'92 transform an individual\'92s ratings of items on the NEI VFQ-25 visual function questionnaire into a 0-4 ordinal rating scale, and then estimates a person measure for that individual using the method of successive dichotomizations, or MSD, which is a polytomous Rasch model that estimates ordered thresholds.\
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To use the program, macros must be enabled (Excel will ask you to do this when opening the file). \
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To estimate a MSD person measure, type in the individual\'92s ratings into the \'93Actual rating\'94 column highlighted in light blue, then press the \'93Estimate person measures with MSD\'94 button. If an invalid rating is entered into the \'93Actual rating\'94 column, the cell with the invalid rating will turn red once the \'93Estimate person measures with MSD\'94 button is pressed, and will remain red until a valid entry is entered and the button is pressed again.\
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MSD will in some cases estimate \'93NA\'94 as the person measure. This literally means that MSD cannot mathematically estimate a person measure. The reasons are either: 1) there are no ratings, or 2) all ratings are one of the extreme scores, i.e., all ratings in the \'93Converted rating\'94 column are either 0\'92s or all are 4\'92s. A popup will appear that provides further information on the minimum or maximum possible value of any person measure that cannot be estimated.}