To ensure the quality of the data included, we additionally required that outcome ascertainment was made through cancer registry linkage.
However, the decision to admit a patient overnight is made by the treating doctor and not by parents, and this should minimize the risk of ascertainment bias.
In this article we propose a new method by which the assessment of completeness of case ascertainment can be made more accurate and the certification process made more reliable.
Although resolution of IAH was a prognostic factor, our study was not designed to focus on therapeutic management of IAH, and no conclusions can be drawn or ascertainments can be made about the strategies that were effective.
The QARCs assess these data against numerous quality indictors to ensure ascertainment is good before being made available for analysis (NHS Breast Screening Programme, 2006).
No explicit correction was made for ascertainment bias.
The US government considered this significant enough to declare the disease service-attributable. 24 However, there remains good reason to believe that the excess is the result of an ascertainment bias, in which greater efforts were made to find cases in Gulf veterans than in control individuals, together with an unusually low rate of ALS in those control individuals.
The estimates of life expectancy could be biased upwards because of under-ascertainment of deaths, but regular attempts are made to minimise this through the triangulation of information on deaths held by the UK CHIC Study, surveillance studies from the Health Protection Agency Centre for Infections, and the death registry of the Office for National Statistics (ONS).
Nevertheless, in most studies, little or no attempt has been made to correct for ascertainment bias, and its effect is currently unknown.
Recently, HAV burden has been computed based on current notification data and estimates of under-reporting/under-ascertainment [ 7], but forecasts have not been made.
