******************************************************************
*STATA syntax code for the computation of index*
*values with the US (Craig & Rand) value set (DCE with duration)*
******************************************************************;

gen disut_mo = .
replace disut_mo = 0 if missing(disut_mo) & mobility == 1
replace disut_mo = 0.021 if missing(disut_mo) & mobility == 2
replace disut_mo = 0.033 if missing(disut_mo) & mobility == 3
replace disut_mo = 0.069 if missing(disut_mo) & mobility == 4
replace disut_mo = 0.111 if missing(disut_mo) & mobility == 5

gen disut_sc = .
replace disut_sc = 0 if missing(disut_sc) & selfcare == 1
replace disut_sc = 0.023 if missing(disut_sc) & selfcare == 2
replace disut_sc = 0.044 if missing(disut_sc) & selfcare == 3
replace disut_sc = 0.067 if missing(disut_sc) & selfcare == 4
replace disut_sc = 0.123 if missing(disut_sc) & selfcare == 5

gen disut_ua = .
replace disut_ua = 0 if missing(disut_ua) & activity == 1
replace disut_ua = 0.016 if missing(disut_ua) & activity == 2
replace disut_ua = 0.025 if missing(disut_ua) & activity == 3
replace disut_ua = 0.045 if missing(disut_ua) & activity == 4
replace disut_ua = 0.072 if missing(disut_ua) & activity == 5

gen disut_pd = .
replace disut_pd = 0 if missing(disut_pd) & pain == 1
replace disut_pd = 0.014 if missing(disut_pd) & pain == 2
replace disut_pd = 0.025 if missing(disut_pd) & pain == 3
replace disut_pd = 0.115 if missing(disut_pd) & pain == 4
replace disut_pd = 0.185 if missing(disut_pd) & pain == 5

gen disut_ad = .
replace disut_ad = 0 if missing(disut_ad) & anxiety == 1
replace disut_ad = 0.025 if missing(disut_ad) & anxiety == 2
replace disut_ad = 0.038 if missing(disut_ad) & anxiety == 3
replace disut_ad = 0.09 if missing(disut_ad) & anxiety == 4
replace disut_ad = 0.101 if missing(disut_ad) & anxiety == 5

gen disut_total = disut_mo + disut_sc + disut_ua + disut_pd + disut_ad 

gen count_gt1 = (mobility > 1) + (selfcare > 1) + (activity > 1) + (pain > 1) + (anxiety > 1)
gen count_gt2 = (mobility > 2) + (selfcare > 2) + (activity > 2) + (pain > 2) + (anxiety > 2)
gen count_gt3 = (mobility > 3) + (selfcare > 3) + (activity > 3) + (pain > 3) + (anxiety > 3)
gen count_gt4 = (mobility > 4) + (selfcare > 4) + (activity > 4) + (pain > 4) + (anxiety > 4)

replace disut_total = disut_total + (-0.006 * count_gt1) + (0.008 * count_gt2) + (0.114 * count_gt3) + (0.023 * count_gt4)

gen EQ_index = . 
replace EQ_index = 1 - disut_total
replace EQ_index = round(EQ_index, .001)