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Chi-square test for equal probabilities of the levels of the grouping variables among the myopic children
| Grouping characteristic | Chi^2 test statistic | Degrees of freedom | P-value |
|---|---|---|---|
| Examination before (yes or no) | 44.085 | 1 | < 0.0001 |
| Children have glasses (yes or no) | 4.339 | 1 | 0.0373 |
| Children wear glasses (yes, no, sometimes) | 119.4 | 2 | < 0.0001 |
