Research software citation: An introduction
Today, software is an integral part of scientific research. It is used to, e.g., create, process, and analyze research data, and model and simulate complex processes.
Despite its critical function for research, however, it is not properly embedded in scientific systems of acknowledgement and reputation. Across disciplines, journal articles, monographs and other traditional forms of scholarly output are still the de facto norm of credit distribution via citation.
The situation has been gradually improving for some forms of research products - notably research data - as stakeholders acknowledge their importance for the reproducibility, verifiability and sustainability of research. Yet, software is often still neglected as the irreplaceable link between hypotheses, (raw) data, and research results and scientific findings.
Arguably, the scholarly ecosystem as such, or at least its processes for acknowledging and crediting research efforts in any form, would have to be transformed into a more ideal state for software to assume its proper place. But until this can be achieved - if it is possible at all - the current system should be leveraged in order to crete a level(er) playing field for software in science.
One obvious lever is software citation.
The state of software citation
Software citation seems to be hard, and for different reasons.
1. Researchers don’t know how to reference software
The ways how software is acknowledged in research publications, for example, is haphazard. Common examples include the following, with decreasing value in terms of acknowledgement of software (cf. Howison & Bullard (2016)).
- Citation of a publication describing the software
- Citation of a user guide
- Citation of a software project website
- Including a URL to a software project website in the text
- Including the name of the software in the text
- Not including a mention of the software at all
Even the superficially beneficial examples - such as a citation of a publication describing the software - are not sufficient, as the authors of the publication may differ from the authors of the software, and because while software keeps changing, it is impossible to keep software publications up to date, or to publish something new for each version of the software.
One main cause for these unsatisfactory citation practices is the following.
2. Software authors don’t publish their software in a citation-friendly manner
There are many ways to publish software, and not all of them are citation-friendly. You can send binaries to colleagues per email, provide them for download from a project website, tag a specific state of the source code on a source code repository platform, deploy build artifacts to a language-specific repository, etc.
These methods, however, aren’t usually on par with the digital publication practices for other scientific publications, where, e.g., a paper is deposited and given an identifier, such as a DOI, which can be used to uniquely identify the citation target in a concise and reliable manner.
Additionally, software authors often fail to visibly provide the metadata required for suitable citation.
3. Software citation metadata is not provided (visibly)
It is easy to cite a book or article, because usually the metadata needed for citation is part of the artifact itself: Authors are listed at least with their family names, and in a determined order; The title of the work is provided as it is a major part of the work’s identity; The time, place of publication are provided, as is any sort of accession number (such as journal issue and volume numbers) that may be needed to unambiguously identify a work.
With software, a product name is sometimes all that is easily recoverable, and perhaps a version identifier.
The above paragraphs, thus, define three key issues for the citation of research software which need to be solved.
Thankfully, the scholarly community is increasingly determined to tackle these issues, and for some of them, solutions have been found or are being developed.
A principles-driven culture change for software citation
The FORCE11 Software Citation Working Group has published a seminal paper, outlining the principles of software citation in science:
Smith, Arfon M., Katz, Daniel S., Niemeyer, Kyle E., & FORCE11 Software Citation Working Group. (2016). Software citation principles. PeerJ Computer Science, 2, e86. https://doi.org/10.7717/peerj-cs.86.
The paper can and should be the baseline for future endeavours in research software citation, and is a must-read for everyone involved or interested in the topic. Ideally, it is the starting point for a real culture change.
Structured software (citation) metadata
Structured metadata is a reliable foundation for enabling better software citation. Two projects specifically are developing schemas and implementations for the provision of software (citation) metadata:
- CodeMeta provides an exchange schema for general software metadata, and an implementation in JSON-LD.
- Citation File Format provides a schema for software citation metadata, and a machine- and human-readable (and writable) format, tailored towards software citation use cases.
Workflows for software citation
Increasingly, stakeholders such as repositories, indexers, etc. develop workflows for the creation, (re-)use, and distribution of software metadata. Much of this work is linking back to the FORCE11 Software Citation Implementation Working Group, whose website and GitHub site provide a good access point for tracking and contributing these endeavours.
- Howison, James, & Bullard, Julia. (2016). Software in the scientific literature: Problems with seeing, finding, and using software mentioned in the biology literature. Journal of the Association for Information Science and Technology, 67(9), 2137–2155. https://doi.org/10.1002/asi.23538.