Table 1.

Hypothetical study population and case-control study with unmatched and matched standard analyses

	Young participants			Old participants			Total				Odds ratio (95% CI)
	Exposed	Not exposed		Exposed	Not exposed		Exposed		Not exposed		Crude	Age adjusted
Total population:
Cases	80	10		100	200		180		210		0.86 (0.70 to 1.05)	2.00 (1.59 to 2.51)*
Non-cases	80 000	20 000		20 000	80 000		100 000		100 000
Unmatched case-control study:
Cases	80	10		100	200		180		210		0.86 (0.65 to 1.14)	2.00 (1.38 to 2.89)
Controls	156	39		39	156		195		195
Matched case-control study standard analysis:
Cases	80	10		100	200		180	210			1.68 (1.25 to 2.24)	2.00 (1.42 to 2.81)*
Controls	72	18		60	240		132	258

*“True” age adjusted.