--------------------------------------------------------------------------------------------------------------- Additional File 1: Principal Component Analysis of household items to create a wealth index . pca Radio Satellite Sewing Refrigerator DVD Computer Fan Phone Bicycle Motocycle Car Principal components/correlation Number of obs = 322 Number of comp. = 11 Trace = 11 Rotation: (unrotated = principal) Rho = 1.0000 -------------------------------------------------------------------------- Component | Eigenvalue Difference Proportion Cumulative -------------+------------------------------------------------------------ Comp1 | 2.678 1.41352 0.2435 0.2435 Comp2 | 1.26448 .108384 0.1150 0.3584 Comp3 | 1.15609 .154077 0.1051 0.4635 Comp4 | 1.00202 .0694149 0.0911 0.5546 Comp5 | .932602 .113624 0.0848 0.6394 Comp6 | .818978 .0515724 0.0745 0.7138 Comp7 | .767406 .0904707 0.0698 0.7836 Comp8 | .676935 .0481808 0.0615 0.8451 Comp9 | .628754 .0662395 0.0572 0.9023 Comp10 | .562515 .0502938 0.0511 0.9534 Comp11 | .512221 . 0.0466 1.0000 -------------------------------------------------------------------------- Principal components (eigenvectors) -------------------------------------------------------------------------------------------------------- Variable | Comp1 Comp2 Comp3 Comp4 Comp5 Comp6 Comp7 Comp8 Comp9 -------------+------------------------------------------------------------------------------------------ Radio | 0.2351 -0.3269 -0.2959 0.4516 -0.3647 -0.2042 0.4168 0.1848 0.3003 Satellite | 0.3547 0.1563 -0.1313 -0.1994 -0.3171 -0.1583 -0.5076 0.5380 0.1561 Sewing | 0.1238 0.3179 0.0147 0.8171 0.2207 -0.0593 -0.3048 0.0032 -0.1997 Refrigerator | 0.4246 -0.1932 0.0760 -0.1006 -0.1182 -0.1385 0.1453 -0.2566 -0.0613 DVD | 0.3713 -0.0501 -0.2163 -0.0319 0.3964 0.0931 -0.2174 -0.4653 0.5769 Computer | 0.3222 0.3787 -0.2724 -0.0809 -0.2972 -0.0314 0.2082 -0.3952 -0.4679 Fan | 0.4124 -0.2355 0.1697 -0.1409 0.0884 -0.1154 -0.3052 0.0028 -0.3332 Phone | 0.2548 -0.4403 0.5102 0.1430 0.1387 0.1221 0.1149 0.1120 -0.1803 Bicycle | 0.1682 0.3374 0.5130 0.0810 -0.4242 0.5105 0.0362 -0.0867 0.3067 Motocycle | 0.1730 0.4560 0.3386 -0.1292 0.3319 -0.5368 0.3969 0.1788 0.1874 Car | 0.2976 0.1155 -0.3183 -0.0858 0.3757 0.5691 0.3144 0.4311 -0.1320 -------------------------------------------------------------------------------------------------------- ------------------------------------------------ Variable | Comp10 Comp11 | Unexplained -------------+--------------------+------------- Radio | 0.2130 -0.1681 | 0 Satellite | -0.0600 0.3036 | 0 Sewing | -0.1750 -0.0128 | 0 Refrigerator | -0.7998 -0.0545 | 0 DVD | 0.1741 0.1388 | 0 Computer | 0.2947 0.2782 | 0 Fan | 0.3284 -0.6266 | 0 Phone | 0.1899 0.5761 | 0 Bicycle | 0.0456 -0.2065 | 0 Motocycle | 0.0773 -0.0427 | 0 Car | -0.1075 -0.1036 | 0 ------------------------------------------------ . . predict wealthscore, score (10 components skipped) Scoring coefficients sum of squares(column-loading) = 1 -------------------------------------------------------------------------------------------------------- Variable | Comp1 Comp2 Comp3 Comp4 Comp5 Comp6 Comp7 Comp8 Comp9 -------------+------------------------------------------------------------------------------------------ Radio | 0.2351 -0.3269 -0.2959 0.4516 -0.3647 -0.2042 0.4168 0.1848 0.3003 Satellite | 0.3547 0.1563 -0.1313 -0.1994 -0.3171 -0.1583 -0.5076 0.5380 0.1561 Sewing | 0.1238 0.3179 0.0147 0.8171 0.2207 -0.0593 -0.3048 0.0032 -0.1997 Refrigerator | 0.4246 -0.1932 0.0760 -0.1006 -0.1182 -0.1385 0.1453 -0.2566 -0.0613 DVD | 0.3713 -0.0501 -0.2163 -0.0319 0.3964 0.0931 -0.2174 -0.4653 0.5769 Computer | 0.3222 0.3787 -0.2724 -0.0809 -0.2972 -0.0314 0.2082 -0.3952 -0.4679 Fan | 0.4124 -0.2355 0.1697 -0.1409 0.0884 -0.1154 -0.3052 0.0028 -0.3332 Phone | 0.2548 -0.4403 0.5102 0.1430 0.1387 0.1221 0.1149 0.1120 -0.1803 Bicycle | 0.1682 0.3374 0.5130 0.0810 -0.4242 0.5105 0.0362 -0.0867 0.3067 Motocycle | 0.1730 0.4560 0.3386 -0.1292 0.3319 -0.5368 0.3969 0.1788 0.1874 Car | 0.2976 0.1155 -0.3183 -0.0858 0.3757 0.5691 0.3144 0.4311 -0.1320 -------------------------------------------------------------------------------------------------------- ---------------------------------- Variable | Comp10 Comp11 -------------+-------------------- Radio | 0.2130 -0.1681 Satellite | -0.0600 0.3036 Sewing | -0.1750 -0.0128 Refrigerator | -0.7998 -0.0545 DVD | 0.1741 0.1388 Computer | 0.2947 0.2782 Fan | 0.3284 -0.6266 Phone | 0.1899 0.5761 Bicycle | 0.0456 -0.2065 Motocycle | 0.0773 -0.0427 Car | -0.1075 -0.1036 ---------------------------------- . . lab var wealthscore "Household asset score based on PCA" . . xtile wealthcat = wealthscore, nq(3) . . lab var wealthcat "Household socioeconomic status (tertile)" . . lab define wealthcat 1 "Low" /// > 2 Medium /// > 3 High . . lab val wealthcat wealthcat . ---------------------------------------------------------------------------------------------------------------