Table 3 Clustering of neurological symptoms according to previous work with pesticides.

Number of symptoms reported*	Never worked with pesticides			Ever worked with sheep dip			Ever worked with insecticides, never with sheep dip			Ever worked with other pesticides, never with sheep dip or insecticides			All subjects
	O†	E‡	O/E§	O†	E‡	O/E§	O†	E‡	O/E§	O†	E‡	O/E§	O†	E‡	O/E§
0	4671	4044.2	1.2	1327	1071.6	1.2	601	493.1	1.2	712	587.8	1.2	7311	6185.8	1.2
1	893	1752.7	0.5	347	666.5	0.5	135	273.8	0.5	165	324.9	0.5	1540	3036.6	0.5
2	302	287.1	1.1	128	155.4	0.8	45	58.5	0.8	55	69.3	0.8	530	565.4	0.9
3	132	23.8	5.5	53	18.2	2.9	31	6.3	4.9	35	7.6	4.6	251	53.3	4.7
4	67	1.1	98.2	27	1.2	47.5	9	0.4	52.6	12	0.5	47.9	115	2.8	73.6
5	28	0.0		21	0.0		9	0.0		8	0.0		66	0.1
6	10	0.0		8	0.0		2	0.0		1	0.0		21	0.0
7	6	0.0		2	0.0		0	0.0		2	0.0		10	0.0

*From the seven symptoms listed in table 1.

†Observed number of subjects.

‡Expected number of subjects if prevalence of each symptom were statistically independent (see text).

§Based on expected numbers rounded to two decimal places.