Code-sharing policies are associated with increased reproducibility potential of ecological findings

Software code (e.g., analytical code) is increasingly recognised as an important research output, as it improves transparency, collaboration, and research credibility. Many scientific journals have introduced code-sharing policies; however, surveys show alarmingly low compliance with these policies. In this study, we expand on a recent survey of ecological journals with code-sharing policies by investigating sharing practices in a comparable set of ecological journals without code-sharing policies. Our aims were to estimate code- and data-sharing rates, assess key reproducibility-boosting features like the reporting of software versioning, and compare reproducibility potential between journals with and without a code-sharing policy. We reviewed a random sample of 314 articles published between 2015-2019 across 12 ecological journals without a code-sharing policy. Only 15 articles (4.8%) provided analytical code, with the percentage nearly tripling over time (2015-2016: 2.5%, 2018-2019: 7.0%). Data-sharing was higher than code-sharing (2015-2016: 31.0%, 2018-2019: 43.3%), yet only 8 articles (2.5%) shared both code and data. Compared with a comparative sample of 346 articles from 14 ecological journals with a code-sharing policy, journals without code-sharing policies showed 5.6 times lower code-sharing, 2.1 times lower data-sharing, and 8.1 times lower reproducibility potential. Despite these differences, key reproducibility-boosting features between the two types of journals were similar. About 90% of all articles reported the analytical software used; however, for journals with and without a code-sharing policy, software version was often missing (49.8% and 36.1% of articles, respectively), and only proprietary (i.e., non-free) software was used in 16.7% and 23.5% of articles, respectively. Our study suggests that journals with code-sharing policies have greater reproducibility potential than those without. Code-sharing policies are likely a necessary but insufficient key step toward increasing reproducibility. Journals should prioritize adopting explicit, easy-to-find and strict code-sharing policies to facilitate researcher compliance as well as implement mechanisms such as checklists to ensure compliance.