While the design of EPICOR was geared to recruiting representative patients from representative centers in each country, we cannot directly verify that centers are indeed representative in respect to adherence to treatment guidelines and other aspects of patient management.
The baseline sample was representative of the population in respect of sex and social class, thereafter differential attrition (e.g. persistent school truants) made it less so.
The baseline sample (age 11 years) was representative of the population in respect of sex and socio-economic status (SES) [ 14].
We cannot know whether our nuclear data set is representative, in this respect, of nuclear loci in general, but examination of the dN/ dS ratios yields no evidence that levels of selective constraint are anomalous (values for the 32 lineages in the main data set range from 0.046 to 0.200 [see Additional file 1], which can be compared to results from complete genomes of primates and rodents [ 76]).
With coverage of approximately 5.7% of the UK population (2009), practices included in the database are broadly representative of practices in the UK in respect of patients' demographics and characteristics [ 16].
It is recognised that findings from randomised clinical trials are not necessarily representative of everyday clinical practice, particularly in respect of patient populations and adherence to medication [ 18, 19].
The cases are representative of suicides in this age group in respect of sex and method of suicide.
The 50 rock pools were a representative sub-set of the 530 rock pools in respect of pool size and presence of vegetation.
The sample remains representative, in most respects, of the British-born population of the same age (Wadsworth et al., 1992, Wadsworth et al., 2003).
Although this might introduce bias, the cohort have been found at age 53 to be representative in most respects of the national population born at a similar time and the distribution of occupational class and unemployment at ages 60 64 was similar to the 2001 England Census reference population.
