<P> The quasi-standard for systematic review in the social sciences is based on the procedures proposed by the Campbell Collaboration, which is one of a number of groups promoting evidence - based policy in the social sciences . The Campbell Collaboration "helps people make well - informed decisions by preparing, maintaining and disseminating systematic reviews in education, crime and justice, social welfare and international development . It is a sister initiative of Cochrane . The Campbell Collaboration was created in 2000 and the inaugural meeting in Philadelphia, USA, attracted 85 participants from 13 countries . </P> <P> Due to the different nature of research fields outside of the natural sciences, the aforementioned methodological steps cannot easily be applied in business research . Early attempts to transfer the procedures from medicine to business research have been made by Tranfield et al. (2003). A step - by - step approach has been developed by Durach et al.: Based on the experiences they have made in their own discipline, these authors have adapted the methodological steps and developed a standard procedure for conducting systematic literature reviews in business and economics . </P> <P> While systematic reviews are regarded as the strongest form of medical evidence, a review of 300 studies found that not all systematic reviews were equally reliable, and that their reporting can be improved by a universally agreed upon set of standards and guidelines . A further study by the same group found that of 100 systematic reviews monitored, 7% needed updating at the time of publication, another 4% within a year, and another 11% within 2 years; this figure was higher in rapidly changing fields of medicine, especially cardiovascular medicine . A 2003 study suggested that extending searches beyond major databases, perhaps into grey literature, would increase the effectiveness of reviews . </P> <P> Roberts and colleagues highlighted the problems with systematic reviews, particularly those conducted by the Cochrane, noting that published reviews are often biased, out of date and excessively long . They criticized Cochrane reviews as not being sufficiently critical in the selection of trials and including too many of low quality . They proposed several solutions, including limiting studies in meta - analyses and reviews to registered clinical trials, requiring that original data be made available for statistical checking, paying greater attention to sample size estimates, and eliminating dependence on only published data . </P>

Which type of review is considered the most rigorous
find me the text answering this question