Most researchers who have encountered the CRediT taxonomy know it as a list of fourteen contribution roles — Conceptualization, Methodology, Software, Investigation, Writing – original draft, and so on — that allows a paper to say who did what rather than relying on a bare author list. But there is a second dimension to CRediT that is less widely understood and frequently underused: the ability to attach a degree of contribution to each role. CRediT is not only about which roles a person played; it can also convey how much they contributed to each, through the qualifiers lead, equal and supporting. Used correctly, these transform a flat list of roles into a far more informative account of a collaboration. This article explains them, drawing on the CRediT extensions domain of the CASRAI Dictionary.
The standard behind CRediT
It is worth recalling that CRediT is not merely an informal convention but a recognised standard. It was formalised as ANSI/NISO Z39.104-2022, the standard maintained through the National Information Standards Organization (NISO). That formalisation matters: it gives CRediT a stable, authoritative definition that publishers, systems and institutions can implement consistently, rather than each interpreting the taxonomy in its own way. Part of what the standard defines is precisely the degree-of-contribution dimension — the provision that each role may carry a qualifier indicating the extent of a person’s involvement. The qualifiers are therefore an official part of CRediT, not an add-on, and understanding them is part of using the taxonomy as it was designed.
What lead, equal and supporting mean
The three degrees are straightforward in concept, and their value lies in applying them honestly. A contributor designated lead for a role had primary responsibility for that aspect of the work — they drove it, took the leading part, bore the main responsibility for it. A contributor marked equal shared responsibility for the role roughly evenly with one or more others; no single person led it, the work was genuinely joint. A contributor marked supporting made a real and acknowledged contribution to the role but in a secondary capacity, assisting rather than leading. The point of the qualifiers is to capture the texture of collaboration that a yes/no assignment misses. Two people might both be credited with Investigation, but if one designed and ran the experiments while the other assisted, “lead” and “supporting” convey that asymmetry truthfully, where listing both would imply a parity that did not exist.
Why the qualifiers matter
The degree qualifiers add value in several ways. They improve accuracy: a contribution statement that distinguishes who led from who assisted is simply a more truthful account of the work. They aid recognition: a researcher who led the methodology and another who supported it both deserve credit, but distinguishing the two does justice to each, and helps those reading the record — hiring panels, promotion committees, collaborators — understand the actual shape of someone’s contribution. And they support fairness in difficult cases. Where contributions are genuinely shared, the equal qualifier provides a recognised way to say so, which is particularly valuable for marking shared leadership of a role without forcing an artificial hierarchy. In each case, the qualifier carries information that the plain list of roles cannot, and that information is exactly what makes a contribution statement useful rather than merely present.
How to apply them in a contributor statement
Applying the qualifiers well is a matter of judgement exercised honestly. Some practical principles help:
- Assign degrees role by role. A person’s degree can differ across roles — lead on Writing – original draft, supporting on Investigation. Consider each role on its own terms rather than assigning one overall level.
- Reserve “lead” for genuine primary responsibility. If several people are all marked lead on the same role, the designation loses its meaning. Lead should identify who actually drove that aspect of the work.
- Use “equal” when it is true, not as a courtesy. The equal qualifier is valuable precisely because it is accurate; applying it to smooth over differences that really exist undermines the honesty the system depends on.
- Do not inflate “supporting” into more than it was, nor dismiss it as trivial. A supporting contribution is a real contribution, properly acknowledged; the qualifier honours it for what it was.
- Agree the assignments among contributors. Degrees, like roles, should be discussed and agreed by the people involved, ideally early, to avoid disputes and to ensure the statement reflects a shared understanding.
The limits and the discipline
The qualifiers are powerful only if they are used with discipline. Their entire value rests on being applied truthfully; a contribution statement in which everyone is “lead” on everything conveys nothing, and one in which degrees are assigned to flatter rather than to describe is worse than none, because it dresses up inaccuracy as precision. The degrees are an invitation to be honest about the real distribution of work, not a set of titles to be distributed for diplomatic convenience. Used with that discipline, they let a contribution statement do justice to the genuine complexity of collaborative research; used carelessly, they merely add noise.
A consistent vocabulary for contribution
For degree qualifiers to mean the same thing across journals, institutions and reporting systems, the taxonomy and its qualifiers must be applied consistently — which is precisely what formalisation as ANSI/NISO Z39.104-2022 enables, and what a shared vocabulary sustains in practice. That consistency is what the CASRAI Dictionary supports: a shared vocabulary so that a role marked lead, equal or supporting is understood the same way wherever it is recorded, whether it travels through a publisher’s system, a repository or an institutional CRIS. CRediT’s roles tell the reader which parts of the work a contributor touched; the degree qualifiers tell them how much. Together, and used honestly, they turn the author list from a question into an answer — a clear, structured account, grounded in good authorship practice, of exactly who did what, and to what extent.