Table 2.
Summary Statistics and Balance Checking
| Variables | (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) |
|---|---|---|---|---|---|---|---|---|---|
| Full Sample (n=2189) | Control (n=510) | Education (n=526) | Free Eyeglasses (n=527) | Education Plus Free Eyeglasses (n=626) | t-Test (P-value) | F-Test (P-value) | |||
| Difference | |||||||||
| (2)–(3) | (2)–(4) | (2)–(5) | |||||||
| 1. Age (Year)-Mean(SD) | 10.51(1.11) | 10.53(1.01) | 10.56(1.20) | 10.47(1.10) | 10.47(1.10) | 0.690 | 0.332 | 0.331 | 0.426 |
| 2. Grade-N (%) | |||||||||
| Fourth | 877(40.1) | 310(60.8) | 307(58.4) | 322(61.1) | 373(59.6) | 0.428 | 0.917 | 0.681 | 0.796 |
| Fifth | 1312(49.9) | 200(39.2) | 219(41.6) | 205(38.9) | 253(40.4) | ||||
| 3. Gender-N (%) | |||||||||
| Male | 1080(49.3) | 269(52.7) | 248(47.2) | 253(48.0) | 310(49.5) | 0.072 | 0.128 | 0.280 | 0.289 |
| Female | 1109(50.7) | 241(47.3) | 278(52.8) | 274(52.0) | 316(50.5) | ||||
| 4. Baseline Vison Knowledge-Mean (SD) | 2.41(1.61) | 2.40(1.59) | 2.25(1.59) | 2.43(1.57) | 2.55(1.66) | 0.137 | 0.783 | 0.112 | 0.017 |
| 5. Knowledge about Myopia-Mean (SD) | 1.25(0.96) | 1.26(0.97) | 1.17(0.96) | 1.28(0.94) | 1.29(0.96) | 0.144 | 0.810 | 0.667 | 0.198 |
| 6. Knowledge about Eyeglasses Importance-Mean (SD) | 1.16(1.08) | 1.14(1.04) | 1.08(1.06) | 1.15(1.08) | 1.27(1.13) | 0.364 | 0.848 | 0.046 | 0.025 |
| 7. Usage Baseline-N (%) | |||||||||
| Yes | 325(14.9) | 85(16.7) | 59(11.2) | 81(15.4) | 100(16.0) | 0.011 | 0.570 | 0.754 | 0.056 |
| No | 1864(85.1) | 425(83.3) | 467(88.8) | 446(84.6) | 526(84.0) | ||||
| 8. Baseline Aware of Being Myopic-N (%) | |||||||||
| Yes | 1000(45.7) | 237(46.5) | 230(43.7) | 249(47.3) | 284(45.4) | 0.357 | 0.872 | 0.712 | 0.706 |
| No | 1189(54.3) | 273(53.5) | 296(46.3) | 278(52.7) | 342(54.6) | ||||
| 9. Living at School-N (%) | |||||||||
| Yes | 521(23.8) | 126(24.7) | 109(20.7) | 129(24.5) | 157(25.1) | 0.126 | 0.918 | 0.900 | 0.305 |
| No | 1668(76.2) | 384(75.3) | 417(79.3) | 398(75.5) | 469(74.9) | ||||
| 10. Baseline LogMAR-Mean (SD) | 0.64(0.21) | 0.62(0.20) | 0.67(0.22) | 0.628(0.20) | 0.63(0.21) | 0.001 | 0.692 | 0.515 | 0.001 |
| 11. Baseline Standardized Math Scores-Mean (SD) | 0.25(0.99) | 0.21(0.20) | 0.24(0.98) | 0.17(0.99) | 0.37(0.95) | 0.570 | 0.584 | 0.007 | 0.004 |
| 12. Father Has High School Education or Above-N (%) | |||||||||
| Yes | 354(16.17) | 87(17.06) | 76(14.45) | 87(16.51) | 104(16.61) | 0.249 | 0.813 | 0.842 | 0.664 |
| No | 1835(83.83) | 423(82.94) | 450(85.55) | 440(83.49) | 522(83.39) | ||||
| 13. Mother Has High School Education or Above-N (%) | |||||||||
| Yes | 247(11.28) | 45(8.82) | 58(11.03) | 61(11.57) | 83(13.26) | 0.237 | 0.144 | 0.018 | 0.133 |
| No | 1942(88.72) | 465(91.18) | 468(88.97) | 466(88.43) | 543(86.74) | ||||
| 14. Both Parents Migrated for Work-N (%) | |||||||||
| Yes | 221(10.10) | 39(7.65) | 65(12.36) | 54 (10.25) | 63(10.06) | 0.011 | 0.144 | 0.157 | 0.096 |
| No | 1968(89.90) | 471(92.35) | 461(87.64) | 473(89.75) | 563(89.94) | 0.120 | 0.462 | 0.814 | 0.141 |
| 15. Household Wealth-Mean (SD) | 2.18(0.79) | 2.19(0.78) | 2.12(0.77) | 2.23(0.80) | 2.18(0.79) | ||||
| 16. Province-N (%) | |||||||||
| Gansu | 802(36.64) | 187(36.67) | 210(39.92) | 171(32.45) | 234(37.38) | 0.282 | 0.153 | 0.804 | 0.087 |
| Shaanxi | 1387(63.36) | 323(63.33) | 316(60.08) | 356(67.55) | 392(62.62) | ||||
Notes: Data source, baseline survey; this table shows the demographic characteristics of different intervention groups and their differences; the characteristics in the full sample, control group, education group, free eyeglasses group, and education plus free eyeglasses group respectively for columns (1)–(5); The difference between sample students in the treatment groups and control group for columns (6)–(8); column (9) suggests the p-value of the joint hypothesis test.