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Systematic reviewers are known for using pre-specified, comprehensive searches to locate all relevant studies for inclusion. This approach to searching, while thorough, may include an overrepresentation of published, statistically significant outcomes if reviewers search only popular databases such as MEDLINE or Embase. This occurrence is known as publication bias, which Dickersin defines as, "the tendency on the parts of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings\cite{Dickersin_1990}". To mitigate this issue, searches should attempt to use alternative information sources that contain grey literature and unpublished data.   A recent survey of Cochrane systematic review authors examined their experiences when retrieving and using unpublished data for systematic reviews. Non-commercial clinical trials registries accounted for 6.3\% of sources reported for use\cite{Schroll_2013}. The infrequent use of trials registries reported by Cochrane reviewers is surprising since they offer promise in locating unpublished trial data. Futhermore, a number of precipitating events have made clinical trials registries a viable information source for systematic reviewers.   In 2005, the International Committee of Medical Journal Editors (ICMJE) created a mandate that all journals included in its vast membership network must require trialists to register prospective clinical trials involving human participants if that trial is to be published in their journal. In 2007, the passage of the Food and Drug Administration Amendments Act (FDAAA) by the United States Government required all researchers conducting clinical trials of humans to register their trials with clinicaltrials.gov, the U.S. clinical trials registry. These two events created an uptake in the number of clinical trials registrations as shown in Figure 1. Most recently, the World Health Organization (WHO) released a position statement in favor of registration of all clinical trials in a publically available, freely accessible, searchable trials registry. The WHO has also issued a list of registries that meet such qualifications.  In light of these events, questions remain regarding the use of clinical trials registries in systematic review searches.    Searching a trial register (clinicaltrials.gov or similar)  is also a good idea and is not time consuming