Numerous authors studied the sensitivity and specificity of [18F]choline PET/CT for the biochemical recurrence of prostate cancers [8 10], but none of them investigated the variability of interpretations of [18F]choline PET/CT examinations.
The aim of this bicentric retrospective observational study was to evaluate the inter- and intra-observer variability of interpretations of [18F]choline PET/CT examinations in patients suffering from biochemical recurrence of prostate cancer following curative treatment.
However, assessing the risk of bias demands a high degree of judgement, is more time consuming, and may result in greater variability of interpretations of the studies [ 9, 115].
Several studies on the assessment of ACR-based density categorization have shown that the inter- and intra-observer variability of interpretations of mammographic densities is only moderate [ 9, 10].
However, the role of liver biopsy as "gold-standard" is subject to increasing debate, owing to possible side effects as well as frequently occurring sampling errors and variability of sample interpretation [ 33].
For example, two years of follow-up can be used to determine if breast cancer develops in studies of variability of radiologists' interpretation of mammography, [ 23] and echocardiography can be used as the reference standard to assess the diagnostic accuracy of physicians identifying cardiac lesion type and severity by auscultation [ 24].
However, many recent studies clearly highlight several crucial drawbacks of liver biopsy, including variable accessibility, high cost, sampling errors and inaccuracy due to inter- and intra-observer variability of pathologic interpretations [ 19].
Thus, despite the presence of hypoxemia, the AECC definition for ARDS may be insensitive to more subtle forms of ARDS because of variability in interpretation of chest radiograph [ 35] and the greater sensitivity of EVLW measures for detecting pulmonary edema [ 36, 37].
In this paper, we show how the separate effects of population substructure and underestimation of variability affect interpretation of G <img src="http://journals.plos.org/plosone/article/asset?id=info?doi/10.1371/journal.pone.0019416.e009.PNG" class= inline-graphic"/> E GWAS results, and we show how this problem can be solved.
These tools include observation of the natural world and/or behavior of living creatures, and experimentation, a method of studying events under controlled conditions that can reduce variability and ambiguity of interpretation.
