A scoping review asks what is out there: how much has been published, of what kinds, on what populations, using what methods, and where the empty spaces are. It is not a lighter systematic review and it is not a narrative review with better paperwork. It is a different question, and once you accept that, most of the method decisions follow. This page is about when the scoping question is the right one and what a protocol has to settle before searching starts.
The question is a map, not a verdict
A systematic review asks whether an intervention works and needs to pool comparable studies to answer it. A scoping review asks what the literature contains and deliberately keeps heterogeneous material in, because variety is the finding. That is why a scoping review usually does not appraise quality or pool results: excluding weak studies would hide part of the map you were drawing.
What a scoping review protocol has to fix in advance
The question and its concept, context and population; the sources to be searched and the search itself; the inclusion criteria; and above all the charting form, which is the scoping equivalent of a data extraction table. Deciding what you will chart before reading is what stops the exercise drifting into a reading list, and it is the part most often left until somebody has already read forty papers.
Where it overlaps with a systematic review and where it does not
The screening machinery is the same: a reproducible search, two people deciding, counts at every stage, and a flow diagram. What differs is the end: a scoping review reports the shape of the evidence and usually the gaps, rather than an effect. If you find yourself wanting to say whether the thing works, you are writing the other kind of review and should stop and change the protocol rather than quietly adding appraisal.
How long it actually takes
Longer than people expect, because breadth means more records to screen rather than fewer. A broad scoping question routinely returns several thousand records where a focused systematic question returns a few hundred, and the screening hours scale with the pile rather than with the depth of reading. The funnel worksheet on this site turns your own record count and screening rates into hours before you commit to the breadth.
Questions people ask about scoping review
What is a scoping review used for?
Mapping a field: how much exists, of what kinds, on whom, and where the gaps are. It is the right choice when the question is what is out there rather than whether something works, and when the material is too varied to pool.
Does a scoping review need a protocol?
Yes, and registering it is normal practice. The part that matters most is the charting form: deciding what you will extract from every source before reading is what keeps the exercise from becoming an annotated reading list.
Do I appraise quality in a scoping review?
Usually not, because excluding weaker studies would distort the map you are drawing. If quality matters to your answer, the question you are asking is probably a systematic-review question.
Is a scoping review easier than a systematic review?
Not necessarily. The breadth means more records to screen, and screening hours scale with the pile. What is lighter is appraisal and synthesis; the front half is often heavier.
Can a scoping review lead to a systematic review?
That is one of its standard uses: map the field, find the sub-question with enough comparable studies, then run a systematic review on that. Doing it in that order saves the wasted systematic review on a question the literature cannot answer.