Gosselin_SCIREP_Data.pdf

A mixed sampling methodology was implemented (Figure 1) to collect journals and articles. First, a selection filter was applied within the Institute for Scientific Information (ISI) Journal Citation Report (https://jcr.clarivate.com) database to generate a list of 504 life science journals. Then, exclusion criteria were applied to the journal list and 245 periodicals were removed. Filters and exclusion criteria are given in Table 1. Using a pseudo-random sequence of 20 numbers between 1 and 259 generated using GraphPad QuickCalc (https://www.graphpad.com/quickcalcs/randMenu), a final shortlist of 20 journals among the 259 preselected ordered by decreasing 2018 Impact Factor were selected (the latest available impact factor at the time of designing this study). Four additional journals were finally excluded either because they were eventually found to be too clinical or because there was no online access granted to the author’s institution, leading to a final list of 16 periodicals (Table 3). Clinical journals were excluded although they may include publications with some preclinical experiments. This was justified to prevent the possible bias created by both the presumed small proportion of such articles in clinical periodicals which would have prompted a larger sampling and the supposed compliance of these studies with clinical guidelines whose standards may be different ^29,30. Fifteen articles per journal were collected by sampling the online contents of each journal, starting from the last issue released in 2019 and browsing backward. This time window was selected to avoid the abundant literature on Coronavirus disease 2019 (Covid-19) published since January 2020, which might show unusual statistical standards. Article inclusion and exclusion criteria are presented in Table 2. Studies using human data were acceptable when they used ex-vivo/in-vitro approaches for extracting tissues, cells or samples. From this intermediate list of 240 articles, 17 were finally excluded during the analysis due to previously unnoticed violations of inclusion criteria or for congruity with exclusion criteria, resulting in a final sample set that included 223 articles. <b> </b><b>Assessment of reporting</b>Each article was explored, and three types of statistical attributes were quantified (Table 4). Indicators of the transparency of study protocols were binary items coded as 0 (presence of all needed information in the text) or 1 (absence of information in the text for at least one figure or table) and were aggregated as proportions of articles that had an insufficiency (non-disclosure) for the given item. The indicators were chosen as the minimum set of information needed by a reader to replicate the statistical protocol: precise sample size (experimental units), well identified test, software and no contradiction. A contradictory information is defined as a mismatch between information provided in different parts of the manuscript although they refer to the same object, such as the disclosure of dissimilar statistical tests (in methods and figure legends) to describe the analysis in one figure or the disclosure of multiple sample sizes for one single set of data. The article structure was assessed using quantitative items, specified as total counts of given items as well as one binary outcome (presence of a statistical paragraph). Qualitative items represented the article content and have been summarised as an inventory of information of interest. In the sampled articles, supplemental methods and information were considered full-fledged methodological information, but supplementary figures and tables presenting results were not eligible for the quantification of statistical insufficiencies, even if they were used to report location tests.