As subjects are sampled based on the case control status and cases are over-sampled, the likelihood depends on distribution of the independent variable (G, E and X) in the population and the case control sampling probability.
Private wells were preferentially sampled based on homeowner requests, possibly causing an overestimate of population-based arsenic exposure, as has been shown in another region of the US [ 54].
Hospital physicians were sampled based on the physician roster of the Soroka University Medical Center and the community-based physicians based on the physician roster of the Southern District of the Clalit Health Services.
A total of 30 bamboos were sampled based on their diameter at breast height (DBH).
Key informants were purposively sampled based on their knowledge on pesticide use, handling and regulation.
In total, 242 sites were sampled based on a random grid cell for soil laboratory measurements.
Compositional gradients were also reflected in a DCA of distance sampled based on species abundance.
Thirty-four participants who were purposefully sampled based on treatment group and intervention response participated in semi-structured interviews.
Secondly, two sub-counties within Isiolo County were sampled, based on the number of camels, the intensity of milk production and level of marketing.
After schools are stratified and sampled, teachers within the schools are also stratified and sampled based on their characteristics (NCES n.d., "Sample selection").
Then, the combined channel H i,nc(t), for each cluster n is sampled based on the delay taps m defined as m = leftlfloor frac{tau_{n}}{T_{s}} rightrfloor, (7).
