Protocol
Iterate citation chaining only when it keeps adding value
Snowballing is useful until it becomes shoveling.
When it fits
- Each backward or forward citation round reveals new directly relevant sources.
When to avoid it
- Formal reviews may require a stricter method and documentation than a practical research task.
Why it matters
When a citation round finds new eligible records with distinct evidence or terminology, use them as new seeds for another bounded iteration. Track the marginal yield. Stop when new rounds mostly produce duplicates, tangential records or no new decision-relevant evidence.
Steps
- Each additional citation round has an explicit reason tied to new relevant yield.
An example
Two new causal-AI papers from the first forward search become seeds; the next round yields only duplicates, so chaining stops.
Check your result
Each additional citation round has an explicit reason tied to new relevant yield.
Keep this limit in mind
- Formal reviews may require a stricter method and documentation than a practical research task.
Evidence and sources
TARCiS recommends another citation-search iteration when newly found eligible records provide useful new seed references.
Iteration adds workload and needs a stopping rationale.
Guidance on terminology, application, and reporting of citation searching: the TARCiS statement · Recommendation 8
Cochrane explicitly discusses when to stop searching and treats search as an iterative process whose stopping point should be justified.
Stopping rules differ between formal completeness-oriented reviews and practical decision research.
Chapter 4: Searching for and selecting studies · When to stop searching