Hi statalist team! I am glad that I participate here! I would like to ask for some help on a "begginer's" problem that I am facing. I made a cross sectional study on a score and variables by checking both eye for each individual. My dataset is:
+---------------------------------------------------------------+
| id eye total center peri sex age surgery D |
|---------------------------------------------------------------|
1. | 1 0 74 17.43 56.5 0 21 1 2 |
2. | 1 1 71 14.04 57.38 0 21 1 2 |
3. | 2 0 82 14.04 68.23 1 22 1 1 |
4. | 2 1 88 15.93 71.86 1 22 1 1 |
5. | 3 0 78 14.87 64.56 0 23 1 2.5 |
|---------------------------------------------------------------|
6. | 3 1 76 9.98 66.33 0 23 1 2.5 |
7. | 4 0 82 13.37 68.23 0 46 1 6 |
8. | 4 1 79 15.93 63.09 0 46 1 6 |
9. | 5 0 73 9.98 63.1 1 22 1 3.5 |
10. | 5 1 68 11.12 56.47 1 22 1 3.5 |
|---------------------------------------------------------------|
11. | 6 0 67 9.98 57.03 0 21 1 2.5 |
12. | 6 1 65 15.93 48.62 0 21 1 2.5 |
13. | 7 0 60 9.98 49.82 0 21 1 2 |
14. | 7 1 68 11.12 56.79 0 21 1 1 |
15. | 8 0 65 13.37 51.83 0 39 1 2.5 |

What is the most proper way to start my model? What is the proper command for mixed linear regress model?
Thank you!!