AQoL-7D VisQoL only algorithm

THIS ALGORITHM IS DESIGNED FOR USE WITH THE DATA FROM THE 6 ITEMS OF THE VisQoL DIMENSION IN THE AQoL-7D INSTRUMENT

The VisQoL is a six item dimension (items 21, 22, 23, 24, 25 26) for measuring the quality of life associated with visual impairment.

The formula in Step 1 below was created to derive dimension index for the 7th dimension of the AQoL-7D utility instrument. The values derived from the formula should not be interpreted as utilities on a life-death scale for use in cost-utility analyses.

*Variable names: For this algorithm, the variables in your questionnaire or database should be named

aqol21, aqol22, aqol23, aqol24, aqol25, aqol26

Raw Data entry: The first response in any item, the item best, is entered as ‘1’, the second as ‘2’, third as '3' and so on.

*Missing Values: Note that missing data are represented by a blank or dot and are handled by imputing values within each dimension. This algorithm allows for 2 missing values.  However, if more item responses in the dimension are missing, the observations will be dropped and there will not be a dimension score or an instrument score for the individual.

Step 1: Save and extract the Zip file, then move either the SPSS Syntax file or STATA file to your preferred directory.

Step 2: Open the file in your program, you may have to change the extension from .txt to .sps (for SPSS) or .do (for STATA)

Step 3: Select Run -> All
This will produce an output file containing the results of the algorithm and some descriptive statistics

Step 4: Finally, please remember that you will need to save the dataset to a new file or overwrite existing file to have the scores available for future use.