Notwithstanding the limitations listed above, the NHTS constitutes the only known nationally representative, population based, data source for road-based travel distance and time for medical/dental care.
We therefore used the linked Surveillance, Epidemiology, and End Results Program-Medicare database, the largest US population based data source within oncology, to describe the relation between interval to radiotherapy and recurrence of breast cancer.
We used data from the Surveillance Epidemiology and End Results (SEER) registry, a nationally representative, population based data source on cancer, linked to Medicare files to compare survival outcomes and rates of serious adverse events among older patients with stages II-IIIA non-small cell lung cancer treated with or without platinum based adjuvant chemotherapy in routine clinical practice.
The main advantages of this study are the large sample size taken from a well validated population based data source and the use of newly established data linkages allowing accurate ascertainment of incident myocardial infarction cases and recorded causes of death.
In addition, the population based data sources used were not subject to the same selection bias as cohort data from a private healthcare organisation.
Other strengths include the size of our cohort and the truly population based data sources we used to characterise cohort members and identify ulcerative colitis outcomes.
Unfortunately the literature that accompanied the population based data sources does not include a description of the scales and tapes used to measure the infants, nor of the accuracy of these instruments.
To compare survival among source populations, each captured (and genotyped) trout was first assigned to its known parents (and hence its source population), based on Mendelian exclusion methods implemented in the SOLOMON package in R (Christie et al. 2013).
We addressed this issue by comparing the cohort members with the source population based on the general practitioner-recorded prevalence rates of various disorders.
We first studied a source population based on the original data set, with a prevalence of DVT of 0.1 (140 cases, 1260 controls), reflecting a relatively rare disease situation that commonly directs case control studies.
