P-values extracted from 11 scientific journals across two years

We examined how the proportion of reported significant results, expressed as p-values, changed with increasing impact factor (IF) We divided the range of IF into three intervals: low (IF&lt;4), medium (4≤IF&lt;8), and high (IF≥8) to ensure that our model was applicable to a broad range of impact factors. We then randomly selected at least two journals for each IF interval for both 2012 and 2014 from journals listed in the Science Citation Index Expanded (http://mjl.clarivate.com/cgi-bin/jrnlst/jloptions.cgi?PC=D) under four subject categories: biodiversity conservation, biology, ecology, and evolutionary biology. We examined 11 journals (lowest IF 0.36 to highest IF 17.95), six journals for both years, whilst we examined three for 2014 and two for 2012 alone. We collected p-values reported in all articles using the free trial version of Examine32 Text Search from Aquila Software. We extracted exact p-values and inexact p-values (e.g. p&lt;0.05). All the inexact p-values were reassigned to six intervals in order to calculate the proportion of significant results (Table A in S1 Text). Due to the ubiquitous use of 0.05 as the alpha level in ecology, we considered p-values below this level as significant. <br>

本研究探讨了以p值（p-value）表示的报告统计学显著结果占比，如何随影响因子（Impact Factor, IF）升高而变化。为确保研究模型适用于广泛的影响因子区间，我们将影响因子划分为三个组别：低影响因子组（IF<4）、中影响因子组（4≤IF<8）与高影响因子组（IF≥8）。随后，我们从科学引文索引扩展版（Science Citation Index Expanded, SCIE，http://mjl.clarivate.com/cgi-bin/jrnlst/jloptions.cgi?PC=D）收录的、隶属于生物多样性保护、生物学、生态学与进化生物学这4个学科类别的期刊中，针对每个影响因子组别，在2012年与2014年分别随机选取至少2种期刊。本次研究共纳入11种期刊（影响因子范围为0.36至17.95），其中6种期刊在2012年与2014年均被纳入，另有3种仅在2014年纳入、2种仅在2012年纳入。我们使用Aquila Software公司的免费试用版Examine32 Text Search工具，采集了所有论文中报告的p值。我们提取了精确p值与非精确p值（例如p<0.05）。为计算显著结果占比，我们将所有非精确p值划分为6个区间（详见补充材料S1文本中的表A）。鉴于生态学领域普遍以0.05作为显著性检验的α水准，我们将低于该阈值的p值判定为具有统计学显著性。