Table 1. Basic information on numbers, gender and the age distribution of the total sample and, separately, of the sample used for the pilot genotyping is given in the top part of the table.

	Overall	Proportion	Pilot	Proportion
Gender
M	1824	0.472	506	0.479
F	1982	0.513	497	0.470
Unknown	59	0.015	54	0.051
Total	3865		1057
Age (in 2009)
<20	8	0.002	0	0.000
20–29	82	0.021	13	0.012
30–39	180	0.047	33	0.031
40–49	462	0.120	66	0.062
50–59	688	0.178	172	0.163
60–69	1161	0.300	295	0.279
70–79	915	0.237	246	0.233
80–89	291	0.075	96	0.091
90–99	21	0.005	12	0.011
>100	10	0.003	2	0.002
Unknown	47	0.012	122a	0.115
Total	3865		1057
MD between grandparental birthplaces
Median (km)	16.05		16.31
25% quartile (km)	2.96		3.72
75% quartile (km)	44.85		48.92
n	3646		893
No. missing	219		65
Orkneya	0		99

The lower part of the table gives the median and 25 and 75% quartiles of the mean distance (MD) between grandparental birthplaces for volunteers who gave information for all four grandparents.

^a99 of the unknown age group in the pilot data are previously collected Orkney samples.¹⁹ These are not included in the overall geocoded data set.