Table 1.

Representation of examined sample to the population (Glaucoma Survey Qatar 2009)

Male					Age group	Female
Population	% (A)	Examined	% (B)	(A-B)/A*		Population	% (A)	Examined	% (B)	(A-B)/A
18,1215	65.3	377	18.7	0.714	40-49	30,390	62.1	339	29.9	0.519
74,163	26.7	1,048	52.0	-0.945	50-59	10,144	20.7	482	42.5	-1.049
15,051	5.4	383	19.0	-2.503	60-69	4,262	8.7	201	17.7	-1.034
4,688	1.7	171	8.5	-4.021	70-79	2,636	5.4	88	7.8	-0.440
2,244	0.8	36	1.8	-1.208	80+	1,471	3.0	24	2.1	0.296
96,146		2,015			Total	18,513		1,134

^*(A-B)/A is the fraction of the population proportion and examined persons proportion. The value (both negative and positive) suggests gap in representativeness of the study sample in the subgroup