Table 3 . Decomposition of the difference in eye care utilization between two economic groups, men and women aged 40 to 64 years, Shahroud, Iran, 2009 .
| No eye care visit | Prediction (%) | 95% CI | P | |||
| Prevalence in High group | 9.94 | 8.75 | 11.14 | <0.001 | ||
| Prevalence in Low group | 24.72 | 22.30 | 27.14 | <0.001 | ||
| Differences (Total Gap) | -14.77 | -17.47 | -12.07 | <0.001 | ||
| Due to endowments (explained)a | ||||||
| Predisposing variables | ||||||
| Age | 1.29 | 0.80 | 1.78 | <0.001 | ||
| Education | -5.27 | -6.38 | -4.15 | <0.001 | ||
| Gender | -1.09 | -1.47 | -0.70 | <0.001 | ||
| Enabling variable | Insurance | -0.63 | -0.98 | -0.29 | <0.001 | |
| Need variable | Presenting vision | -0.34 | -0.65 | -0.03 | 0.032 | |
| Sub Total Gap (explained part) | -6.04 | -11.03 | -6.43 | <0.001 | ||
| Due to coefficients (unexplained)b | ||||||
| Predisposing variables | ||||||
| Age | -15.42 | -33.99 | 3.14 | 0.103 | ||
| Education | 2.71 | -0.25 | 5.68 | 0.073 | ||
| Gender | -4.14 | -5.94 | -2.35 | <0.001 | ||
| Enabling variable | Insurance | -3.93 | -13.95 | 6.09 | 0.442 | |
| Need variable | Presenting vision | 0.43 | -0.06 | 0.93 | 0.085 | |
| Constant | 11.63 | -10.09 | 33.35 | 0.294 | ||
| Sub Total Gap (unexplained part) | -8.73 | -11.03 | -6.43 | <0.001 | ||
CI= Confidence Interval; a= Part of gap that related to differences in independent variables between two groups; b= Part of gap that related to differences of coefficients (β) of regression models in two groups.