******************************************************************************************* *******STATA ALGORITHM FOR VISQOL DIMENSION OF THE AQOL-7D INSTRUMENT FOR GENERAL POPULATION (WITH MISSING VALUES) (CHE version 5 date 30 November 2016) **** ********************************************************************************** * THIS ALGORITHM (CHE version 5 date 30 Nomember 2016) MAY BE CHANGED WITHOUT NOTICE. * RESEARCHERS SHOULD CHECK WITH THE AQOL GROUP AT MONASH UNIVERSITY * FOR ANY MODIFICATION www.aqol.com.au*** ********************************************************************************** *This file analyses the six items of the VisQoL dimension (the 7th dimension) of the AQoL-7D instrument and produces a VisQoL Dimension Value (not utility) which is ** then mapped to produce a PREDICTED AQoL-7D UTILITY. ***(Dimension scores are referred to as 'values' and 'disvalues' and are NOT utility scores as they have not been evaluated on a life-death scale).* ** If you have complete AQoL-7D data, use the AQoL-7D algorithm to obtain dimension values (not utilities) and the overall utility score. ** If necessary contact angelo.iezzi@monash.edu *************************************************************** ** Variable names: The AQoL-7D has 26 items; the last dimension, VisQol, covers items 21, 22,23,24,25 and 26. For this algorithm, the variables in your questionnaire ** or database should be named "aqol21, aqol22, aqol23, aqol24, aqol25,aqol26". **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 except for items 23 and 24. **In item 24 response level 7 is scored the same as level 2 (0.018) and in item 24 response level 6 is scored the same as response 1 (o.o) ************************************************************* * The dimensions are scaled on a "Dimension Worst Health State - Dimension Best Health State" scale * where DWHS = 0.00 and DBHS = 1.00. ************************************************************* *Missing Values: Note that missing data are represented by a blank and are handled by imputing values within the 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. ********************************************************************************** * aqol# are item responses in your data * dvQ# are item disvalues * Missing values represented by a blank or dot.** g Q21 = aqol21 g Q22 = aqol22 g Q23 = aqol23 g Q24 = aqol24 g Q25 = aqol25 g Q26 = aqol26 ***************************************************************** ********* Imputing Values Missing in Database ********* ******************************** *** Visqol - Dimension 7 ***** ******************************** egen DVIS_miss = rowmean(Q21 Q22 Q23 Q24 Q25 Q26) egen DVISmissno = rowmiss(Q21 Q22 Q23 Q24 Q25 Q26) replace Q21=round(DVIS_miss) if missing(Q21) & DVISmissno <3 replace Q22=round(DVIS_miss) if missing(Q22) & DVISmissno <3 replace Q23=round(DVIS_miss) if missing(Q23) & DVISmissno <3 replace Q24=round(DVIS_miss) if missing(Q24) & DVISmissno <3 replace Q25=round(DVIS_miss) if missing(Q25) & DVISmissno <3 replace Q26=round(DVIS_miss) if missing(Q26) & DVISmissno <3 *********ITEM DISVALUES********* ***Dimension 7. Visqol ***21. Injure generate dvQ21=0 if Q21==1 replace dvQ21=0.096 if Q21==2 replace dvQ21=0.386 if Q21==3 replace dvQ21=0.687 if Q21==4 replace dvQ21=1 if Q21==5 ***22. Cope with demands generate dvQ22=0 if Q22==1 replace dvQ22=0.019 if Q22==2 replace dvQ22=0.143 if Q22==3 replace dvQ22=0.360 if Q22==4 replace dvQ22=0.751 if Q22==5 replace dvQ22=1 if Q22==6 ***23. Friendships generate dvQ23=0 if Q23==1 replace dvQ23=0.018212 if Q23==2 replace dvQ23=0.226340 if Q23==3 replace dvQ23=0.505963 if Q23==4 replace dvQ23=0.764346 if Q23==5 replace dvQ23=1 if Q23==6 replace dvQ23=0.018212 if Q23=7 ***24. Assistance generate dvQ24=0 if Q24==1 replace dvQ24=0.093 if Q24==2 replace dvQ24=0.295 if Q24==3 replace dvQ24=0.683 if Q24==4 replace dvQ24=1 if Q24==5 replace dvQ24=0 if Q24==6 ***25. Roles generate dvQ25=0 if Q25==1 replace dvQ25=0.014 if Q25==2 replace dvQ25=0.142 if Q25==3 replace dvQ25=0.377 if Q25==4 replace dvQ25=0.733 if Q25==5 replace dvQ25=1 if Q25==6 ***26. Confidence generate dvQ26=0 if Q26==1 replace dvQ26=0.012 if Q26==2 replace dvQ26=0.1291 if Q26==3 replace dvQ26=0.342 if Q26==4 replace dvQ26=0.670 if Q26==5 replace dvQ26=1 if Q26==6 ******************* MODELLING DIMENSION ************** *************************************************** ***DIMENSION 7 - VISQOL **DIMENSION SCALING CONSTANT kD7=-0.833 ***VIS HAS 6 ITEMS ***ITEM WORST WEIGHTS (Wi) *w21= 0.2696557 * w22= 0.3697268 * w23= 0.3078306 * w24= 0.2971339 * w25= 0.3286885 * w26= 0.2810792 generate dD7score=(1/-0.833)*[(1+(-0.833*0.2696557*dvQ21))*(1+(-0.833*0.3697268*dvQ22))*(1+(-0.833*0.3078306*dvQ23))*(1+(-0.833*0.2971339*dvQ24))*(1+(-0.833*0.3286885*dvQ25))*(1+(-0.833*0.2810792*dvQ26))-1] **Item Scores generate INJURE=1-dvQ21 generate COPE=1-dvQ22 generate FRIENDSHIPS=1-dvQ23 generate ASSISTANCE=1-dvQ24 generate ROLES=1-dvQ25 generate CONFIDENCE=1-dvQ26 generate D7score=1-dD7score label var D7score "VisqolDimensionScore"