case	control	scar	age	obstype
2	19312	NA	2.5	strata
25	17327	NA	7.5	strata
50	13172	NA	12.5	strata
44	10325	NA	17.5	strata
39	8026	NA	22.5	strata
47	5981	NA	27.5	strata
53	6479	NA	32.5	strata
1	24	no	2.5	retro
1	31	yes	2.5	retro
11	22	no	7.5	retro
14	39	yes	7.5	retro
28	23	no	12.5	retro
22	27	yes	12.5	retro
16	5	no	17.5	retro
28	22	yes	17.5	retro
20	9	no	22.5	retro
19	12	yes	22.5	retro
36	17	no	27.5	retro
11	5	yes	27.5	retro
47	21	no	32.5	retro
6	3	yes	32.5	retro
