But even if they could argue that the tissue samples were truly randomly sampled from all retinal areas, they would need to provide a much clearer analysis (e.g., based on the S/M opsin gradients in Applebury et al., 2000; Yang et al., 2011; Daniele et al., 2011) of the predictions of the S/M sensitivity of cones for their sampling method.
Because all of the observations made in this study are based on a single male/coalition, a small female group, and a small subadult male group, we do not have a sample of truly independent samples and the conclusions should be viewed as preliminary, and will hopefully stimulate further work in this area.
As truly representative sampling was not feasible the pathfinder sampling method was adopted incorporating sufficient examination sites to cover relevant groups of the population intended [ 21].
As truly representative sampling was not feasible, the pathfinder sampling method was adopted to cover relevant groups of the population intended [ 22].
Although we gathered data from a large group of students over two semesters, all of the students in this study attended the same university and therefore are probably not a truly random sampling of all high school graduates.
Obtaining a truly representative sampling across many countries is always difficult; nonetheless, data across as broad a population as possible were carefully collected in this multicenter study.
This latter approach does not provide a truly random sampling of the genome since regions in which the restriction site for the particular enzyme used for library construction is under-represented will also be under-represented.
We refer to these libraries as "semirandom" relative to the RAD approach; truly random sampling would have employed nonspecific DNA fragmentation, while a more precisely targeted approach would have employed a narrower fragment range.
Nonetheless, the approaches here provide a first, albeit imperfect, approximation of various features of a previously unexplored genome, and several of our conclusions do not depend upon a truly random sampling of the genome.
First, phenotype definitions should capture a truly extreme phenotype, as sampling from extremes can be a powerful way to examine HIV biology.
Sampling only truly fertile women reduced bias as it excluded sterile women who will never be able to conceive and for whom factors leading to female fertility impairment may be different.
