Multiple scientific and lay organisations collaborated with headache experts in these countries, and not all were able to draw population-based samples.
This is frequently the case for volcanic fields (regions of distributed volcanism) where low eruption rates, fertile soil, and attractive landscapes draw populations to live close by.
The aim was to draw population-representative samples with a minimum of 2000 people aged 50+ completing the core ABC measure in each country.
The general agreement between our initial population genetic analysis and previous population genomic studies (Begun and Aquadro 1993; Langley et al. 2012) would seem to confirm that our data are of sufficient quality to allow for drawing population genetic inferences.
Furthermore, a prevailing understanding was community visits could be substituted by consulting patients in out-patient clinic which draws population from all surrounding communities and " students get ample opportunities to interact with patients from poor neighbourhoods".
In Canada, a General Practice Rurality Index was introduced in 1997 including remoteness from closest basic/advanced referral centre, drawing population, number of GPs, number of specialists and presence of an acute-care hospital [ 17].
"Each defeat generally required a huge update or change of ownership to draw the population back".
On average across participating countries, a probability-based sample of more than 5000 adults was drawn, following population registries or household registries where population registries were unavailable.
Second, individuals are drawn from population registers using citizenship, place of birth and name.
So, two smaller rural counties would share one state senator instead of having a senator by districts that are drawn by population.
Future biomass estimations of adults or juveniles should consider spatiotemporal variation in abundance when drawing on population indices.
