Table.

A hypothetical distribution of negative tests for colorectal cancer during the previous 10 years among controls and persons who later died from colorectal cancer. (Indication for the test could not be documented from information available to the study.)

Time of test prior to the case’s diagnosis	Fatal case	Control	Odds ratio
1–2 years	2	18	0.07
3–5 years	18	22	0.49
6–9 years	30	30	0.60
No test	50	30	1.00
	100	100

^aReference category