Choosing the Right Literature Review Method

Choose the literature review method that can answer the research question and deliver the intended review purpose within the defined scope, then validate that fit against the evidence base, required rigour and transparency, and feasibility. As a starting fit, focused evaluative questions commonly point toward a systematic review; broad evidence mapping toward a scoping review; interpretive or contextual synthesis toward a narrative review; mixed empirical and conceptual integration toward an integrative review; and time-constrained evidence synthesis may justify a rapid review when its methodological shortcuts are explicit.

Method labels are not a universal ranking. Keep method selection separate from study-level inclusion and exclusion rules and from later search planning: first establish functional fit, then test whether the evidence, transparency requirements and available resources allow credible execution.

Table of Contents⌄

Match the Review Method to the Research Question, Purpose, and Scope

Research question, review purpose, and scope should be evaluated together because each constrains method suitability.

These decision criteria establish the conceptual fit required for method selection before evidence, rigour, and feasibility are assessed.

The three criteria are interdependent rather than isolated checkboxes: changing the question can alter the intended function or appropriate boundaries of the review, while changing its purpose or scope can narrow or broaden the set of suitable methods.

The criteria therefore need to be interpreted together when assessing a review method.

• Research question: inspect what the question must answer and how focused or exploratory that answer needs to be; this condition shapes which review methods can address the question appropriately.
• Review purpose: identify the intended function and outcome of the review; a method is suitable when its analytical function aligns with that purpose.
• Scope: assess the required breadth, depth, boundaries, and expected evidence volume; these conditions constrain which methods can cover the evidence at the required level of detail.

These criteria guide method selection without replacing detailed descriptions of the types of literature reviews or their individual procedures.

Once conceptual fit is established, method suitability can be assessed against the evidence base, required rigour, and practical feasibility.

Match the Method to the Kind of Question the Review Must Answer

The research question constrains what a suitable review method must be capable of answering.

Its breadth and the kind of answer sought change the demands placed on evidence synthesis and therefore affect method suitability.

Question form changes the evidence-synthesis burden in several ways, so these characteristics should be treated as criteria rather than fixed method assignments.

• Focused question: a tightly bounded question narrows the evidence to be addressed and can support a more structured evidence synthesis.
• Broad or exploratory question: wider boundaries place greater emphasis on characterising or mapping the evidence landscape rather than resolving one narrowly specified issue.
• Evaluative or mapping question: an evaluative question requires a method capable of assessing evidence against the intended outcome, while a mapping question requires systematic characterisation of what evidence exists.
• Explanatory or integrative question: questions seeking explanation or integration require a review method capable of relating findings, concepts, or patterns rather than only identifying their presence.

For example, a focused effectiveness question may be compatible with structured evidence synthesis, whereas a broad evidence-mapping question may require an approach that characterises the range and distribution of available evidence.

Choosing a method from these characteristics is separate from learning how to formulate the research question; the relevant criterion here is how question form changes the capabilities required of the review method.

Match the Method to the Review Purpose

The review purpose should guide method choice because it defines the intended function the review must perform, not merely its subject matter.

Different intended outcomes create different methodological requirements, although method suitability can also depend on the available evidence and disciplinary context.

The main purpose distinctions can be organised by the capability a review method must provide.

• Focused answer: an evaluative purpose calls for a method capable of synthesising relevant evidence around a clearly defined outcome or issue.
• Evidence mapping: a purpose centred on broad coverage requires systematic characterisation of the evidence landscape, including its range and key concepts.
• Integrate findings: bringing together diverse evidence requires a method that can relate findings across relevant studies, perspectives, or forms of evidence.
• Critical synthesis: an interpretive or conceptual purpose requires analytical capability to examine relationships, assumptions, tensions, or patterns across the literature.

For example, two reviews may address the same topic while one seeks a focused answer and the other aims to map the available evidence.

Their shared topic does not make their methodological requirements identical because each intended function places different demands on the review.

Review purpose should therefore change the capabilities considered during method choice while remaining consistent with the research question.

Match the Method to the Breadth and Depth of the Scope

Literature review scope affects method suitability because its breadth and depth change the methodological burden of covering and synthesising evidence.

A broader scope increases the coverage requirement, while tighter review boundaries can support deeper synthesis of a more narrowly defined evidence base.

Scope is multidimensional, so method choice should consider how its main dimensions alter the coverage and synthesis required.

• Topic breadth: wider subject boundaries broaden the range of concepts and evidence requiring coverage, while tighter boundaries concentrate the synthesis.
• Population and context boundaries: including more populations or contexts expands the evidence that a method must accommodate; tighter boundaries limit that coverage requirement.
• Time span: a longer period can increase the range of literature and changes that require consideration, whereas a shorter period narrows the temporal boundary.
• Disciplinary spread: coverage across multiple disciplines may require a method capable of handling more diverse terminology, evidence traditions, and forms of interpretation.
• Evidence volume: a larger expected evidence base increases the burden of organising and covering relevant material, while a smaller bounded evidence base can permit more concentrated synthesis.

Broad exploratory coverage places greater emphasis on mapping and characterising an evidence landscape, whereas a narrow scope can support more in-depth synthesis within defined boundaries.

This contrast affects method suitability without making a broad or narrow scope automatically equivalent to any named review method.

Using scope as a selection criterion is distinct from defining the literature review scope in detail.

Separate Method-Selection Criteria from Study Inclusion and Exclusion Criteria

Method-selection criteria determine which review method is suitable for the research question and scope.

Inclusion criteria and exclusion criteria instead govern study eligibility after the review approach and question are defined.

The two criterion sets therefore operate at different decision stages.

The comparison separates the strategic decision about the review method from later study-selection rules applied during screening.

Purpose, timing, examples, and consequences clarify what each criterion set decides.

Comparison point	Method-selection criteria	Inclusion and exclusion criteria
Purpose	Determine which review approach is suitable for the question the review must answer.	Determine which individual studies are eligible to enter the review.
Timing	Apply when choosing and justifying the review method.	Apply after the approach and research question are defined, including during screening.
Examples	Fit with the research question, review purpose, and scope.	Publication date, language, population, context, or study design.
Consequence	Affect the methodological rationale for choosing the review approach.	Affect which studies are included or excluded from the evidence base.

Conflating these criterion sets can make a review method appear justified by procedural eligibility filters rather than its fit with the research question.

Keeping the decision stages separate preserves the methodological rationale while leaving inclusion criteria and exclusion criteria to govern study eligibility.

Assess Method Suitability Against the Evidence, Rigour, and Feasibility

Method suitability requires more than conceptual fit with the review question, purpose, and scope.

A review method must also be assessed against the evidence characteristics, required rigour and transparency, and feasibility of credible execution.

These three checks test different aspects of executable suitability after conceptual fit has been established.

Each asks whether the method can work with the evidence base, meet the required standards of rigour and transparency, and remain feasible under practical constraints.

They qualify method suitability without creating a universal score or assuming that greater complexity produces a better review.

Three executable-fit checks

Evidence suitability

evidence characteristics such as breadth, maturity, and synthesis demand affect whether a method can support the required form of analysis.

Rigour and transparency

the required level of protocol, documentation, transparency, and reproducibility affects what the review method must support for credible execution.

Feasibility

available time, resources, expertise, and other practical constraints may limit which conceptually appropriate methods can be executed credibly.

Method suitability is therefore conditional on both methodological fit and practical fit, rather than on convenience or resource intensity alone.

Feasibility should constrain how an appropriate method is executed or selected among suitable options, not override its ability to answer the review question.

The following assessments examine evidence, rigour, and feasibility as separate dimensions of executable suitability.

Consider the Breadth and Maturity of the Available Evidence

The evidence base affects method suitability because its breadth, maturity, density, and heterogeneity limit what a review can realistically support.

An established and coherent body of evidence may permit more focused synthesis, while emerging or uneven coverage may favour broader characterisation before narrower synthesis is feasible.

Breadth and maturity are distinct attributes, so the evidence base should be assessed across several states rather than treated as simply large or small.

• Emerging versus established literature: emerging literature may have unsettled concepts, developing terminology, or incomplete coverage, which can favour a method that first characterises the evidence landscape. Established literature may support more focused synthesis when the body of evidence is sufficiently developed for that purpose.
• Sparse versus dense evidence: sparse evidence limits how narrowly a review can synthesise a question without overstating what the literature supports. Dense evidence can support more concentrated synthesis, although evidence volume alone does not determine the review method.
• Coherent versus heterogeneous evidence: relatively coherent evidence can reduce the methodological burden of comparing findings, while heterogeneous evidence increases the need to accommodate variation in concepts, populations, contexts, or study designs.

For example, an emerging field with sparse and heterogeneous evidence may be better suited initially to mapping what evidence exists than to forcing a narrowly focused synthesis.

The implication is conditional: evidence-base characteristics shape what a method can credibly accomplish, but they do not replace separate appraisal of source quality.

Consider the Kind of Evidence the Review Must Synthesize

Evidence type affects method suitability because different evidence forms create different synthesis demands.

The chosen method must be capable of combining the relevant material without treating evidence type alone as a complete method selector.

Quantitative evidence, qualitative evidence, mixed evidence, empirical evidence, and conceptual material can place different demands on synthesis.

The relevant distinction is the capability needed to combine findings that are relatively homogeneous or heterogeneous.

• Quantitative evidence: comparable numerical outcomes can support structured synthesis, while substantial heterogeneity may limit how directly results can be combined and increase the required analytical flexibility.
• Qualitative evidence: themes, experiences, meanings, or interpretations require a method capable of synthesising relationships and patterns while preserving relevant contextual differences.
• Empirical evidence: findings derived from observations or studies can be combined when the method accommodates their relevant designs, measures, and forms of reported results.
• Conceptual material: theories, models, and conceptual arguments require synthesis that can relate constructs, assumptions, agreements, and differences rather than treating them as directly comparable empirical findings.
• Mixed or heterogeneous evidence: combining quantitative evidence, qualitative evidence, empirical findings, or conceptual material increases the integration required and may favour a method with sufficient capacity to relate different forms of findings.

For example, a review combining statistical findings, qualitative accounts, and competing conceptual models needs integrative capability across those evidence forms rather than a simple qualitative-versus-quantitative classification.

Method suitability therefore depends on whether the chosen method can support the synthesis demand created by the evidence that must be combined.

Consider the Required Level of Rigour and Transparency

The required level of rigour and transparency should match the review question, intended use, and strength of the claims the review must support.

Method suitability therefore depends on whether the review approach can provide the methodological controls and documentation appropriate to those claims.

The relevance of individual controls varies by review purpose, approach, discipline, and expected use.

Each requirement should be assessed for the condition it addresses and the level of transparency or reproducibility the review needs to support.

• Protocol: an explicit protocol may be expected when decisions need to be specified in advance and documented consistently, which favours methods able to support transparent planning and later comparison with the stated approach.
• Reproducible searching: when readers need to understand how evidence was identified, the method should support sufficiently documented search methods for the search process to be repeated or evaluated.
• Transparent screening: when study selection materially affects the review's claims, the approach should support clear documentation of how records were assessed and why evidence was included or excluded.
• Critical appraisal: when conclusions depend on the credibility or limitations of included evidence, method suitability may depend on whether the approach can incorporate an appropriate form of critical appraisal.
• Documented synthesis: when the review makes interpretive or evidential claims across sources, the method should support a transparent account of how findings were combined, compared, or interpreted.

Methodological rigour is not the same as procedural complexity; adding more formal steps does not by itself make a method more suitable.

Reporting guidance can support transparency and documentation, but it does not independently determine which review method should be selected.

Method choice should remain tied to the review's intended claims, with reporting requirements applied as a separate consideration.

Consider Time, Resources, and Methodological Expertise

Feasibility affects whether a conceptually suitable review method can be executed credibly under the available time, resources, team capacity, database access, and methodological expertise.

These practical constraints should shape the execution plan without replacing fit with the research question, review purpose, and scope.

Hard feasibility constraints should be distinguished from preferences because only constraints that threaten credible execution justify design adjustment.

• Time: a binding timeline can limit the amount of searching, screening, appraisal, or synthesis that can be completed credibly; the legitimate response may be to narrow the scope or revise the project timeline.
• Resources and team capacity: limited staffing or operational capacity can constrain workload-intensive review activities, which may require redistributing tasks, reducing scope, or adjusting the execution plan.
• Database access: restricted access to relevant evidence sources can limit coverage and should prompt reconsideration of access arrangements or review boundaries rather than silent acceptance of incomplete retrieval.
• Methodological expertise: limited experience with the required methods can affect execution quality, but the constraint may be mitigated through training, collaboration, supervision, or a narrower design.
• Preferences: convenience, familiarity, or personal preference may influence workflow choices, but they do not independently justify selecting a review method that fits the research question less well.

For example, a project with a fixed deadline and limited methodological expertise may need a narrower scope or revised execution plan rather than a different review purpose.

Feasibility therefore constrains how the work is designed and delivered, while methodological fit remains the basis for method selection.

Apply a Decision Framework to Narrow and Validate the Candidate Methods

A decision framework is a conditional sequence for narrowing candidate methods until the remaining option is coherent with the review's requirements.

It supports method selection by testing conceptual fit first, then evidence fit, rigour, feasibility, and final validation.

The sequence organizes previously established criteria into one transparent decision path rather than a scoring system.

Each checkpoint tests whether a candidate should be retained, eliminated, or reassessed before the process continues.

1. Test conceptual fit: assess whether each candidate aligns with the research question, review purpose, and scope. Eliminate candidates that cannot address these requirements; if the requirements themselves remain unclear, reassess the review design before continuing.
2. Test evidence fit: determine whether the candidate can handle the available evidence characteristics and synthesis demand. Retain methods that can support the evidence base; eliminate or reassess candidates that cannot accommodate the material to be combined.
3. Test rigour and transparency: assess whether the candidate can support the methodological controls and documentation required by the intended claims. If the required level cannot be supported credibly, eliminate the candidate or revise the review design where appropriate.
4. Test feasibility: determine whether the candidate can be executed credibly within practical constraints such as time, resources, access, and methodological expertise. If execution is not feasible, reassess scope or the execution plan before substituting a weaker-fitting method.
5. Validate final alignment: confirm that the surviving candidate remains coherent across conceptual fit, evidence fit, rigour, and feasibility. If any dimension remains unresolved or contradictory, reassess the relevant decision rather than forcing a final choice.

Validation is the final checkpoint because a method can pass individual tests yet still conflict with the review design when considered as a whole.

The framework narrows and validates candidate methods without replacing reporting guidance, protocols, or later operational planning.

A defensible choice should proceed to implementation only after this final alignment has been established.

Eliminate Methods That Conflict With the Question, Purpose, or Scope

A candidate method should be eliminated when it cannot answer the research question or support the intended review purpose and scope.

Elimination should therefore be based on functional incompatibility, not on whether a method is unfamiliar, demanding, or uncommon.

The following rules identify conflicts that prevent a candidate method from performing the required review function.

• Research-question conflict: exclude a candidate method when its analytical function cannot produce the kind of answer the research question requires.
• Review-purpose conflict: exclude a method when it cannot support the intended function of the review, such as evaluation, mapping, integration, or interpretation.
• Scope conflict: a method oriented toward broad mapping may be incompatible with a narrowly evaluative focused synthesis, while a highly focused approach may conflict with the need to characterise a wide and heterogeneous field.
• Functional versus practical difficulty: functional mismatch can justify elimination, whereas unfamiliarity, workload, or methodological difficulty should be considered later as feasibility or trade-off issues.

For example, rejecting a broad-mapping approach is justified when the review requires a tightly focused evaluative synthesis, not merely because another method is more familiar.

Applying elimination rules this way leaves only candidate methods that remain functionally compatible with the research question, review purpose, and scope.

Compare the Remaining Methods Against the Same Criteria

Shortlisted methods should be compared against the same comparison criteria so differences reflect contextual fit rather than unequal standards.

Candidate methods may differ in question fit, purpose fit, scope fit, evidence fit, rigour, feasibility, and expected output.

The comparison should apply each decision dimension consistently to every shortlisted method.

Where a candidate's characteristics are not yet established, record the relevant limitation rather than assuming a difference.

Common candidate methods compared on the same decision criteria

Comparison criterion	Systematic review	Scoping review	Narrative review
Question fit	Usually strongest for a clearly bounded question that requires a focused synthesis.	Usually strongest for broad or exploratory questions about the extent, characteristics or gaps in evidence.	Usually strongest for interpretive or contextual questions about concepts, theories, developments or debates.
Purpose fit	Provide a comprehensive and transparent synthesis of evidence relevant to a defined question.	Map the evidence landscape, clarify concepts, describe evidence types and identify gaps.	Explain, contextualise or critically synthesise a body of literature without making exhaustive coverage the defining function.
Scope fit	Typically narrower and more explicitly bounded.	Can accommodate broad populations, concepts, contexts and source types.	Can be flexible in breadth, but the boundaries and selection rationale still need to be explicit.
Evidence fit	Can include different study designs when the synthesis method matches them; meta-analysis is optional and only appropriate when data are sufficiently comparable.	Well suited to heterogeneous, emerging or widely distributed evidence when the goal is characterisation rather than pooled effect estimation.	Can combine empirical, conceptual and theoretical literature through an interpretive synthesis, provided the selection logic is transparent.
Rigour and transparency	Normally requires explicit, reproducible methods for searching and selecting evidence; critical appraisal is commonly part of the design.	Uses structured and transparent searching and selection; critical appraisal may be included when it serves the review purpose but is not always the central function.	Transparency varies by design; credible reviews should still explain how literature was located, selected and synthesised.
Feasibility	Often resource-intensive because comprehensive searching, screening, appraisal and synthesis require substantial time and expertise.	Broad coverage can create a large screening workload even when the synthesis is primarily descriptive or mapping-oriented.	Operationally more flexible, but a credible review still requires disciplined scope control, selection rationale and synthesis.
Typical output	A focused evidence synthesis; may include quantitative pooling when the evidence supports it.	A structured map of evidence characteristics, concepts, source types and research gaps.	An interpretive synthesis of themes, concepts, theories, developments or debates.

The decision-relevant trade-off is whether each method's strengths and limitations align with the specific review context, not whether one has the longest procedural checklist.

When these approaches remain on the shortlist, it can be useful to compare systematic, narrative and scoping reviews using the same comparison basis.

Contextual fit should determine which candidate is better aligned with the review requirements without implying a universal winner.

Resolve Trade-Offs Between Methodological Fit and Practical Constraints

Methodological fit should remain aligned with the research question and review purpose even when practical constraints make execution more difficult.

Feasibility may require scope adjustment, timeline changes, or resource changes, but it should not justify selecting a method that cannot support the intended review function.

Trade-offs should therefore distinguish non-negotiable methodological requirements from practical variables that can legitimately be revised.

• Preserve question and purpose fit: retain methods that can answer the research question and support the review purpose; a method remains unsuitable when practical convenience requires abandoning that alignment.
• Preserve required rigour: maintain the level of methodological rigour needed for the intended claims, even when execution must be simplified in other ways.
• Adjust practical variables where legitimate: scope can be narrowed, a timeline can be extended, or resources can be reorganized when these changes preserve methodological integrity and the intended review purpose.

For example, if the strongest-fitting method cannot be completed credibly within the available timeline, narrowing the scope may preserve both the research question and required rigour.

The legitimate trade-off is therefore an adjustment to scope, timing, or execution conditions rather than a change to a method that no longer fits the review's purpose.

Validate Alignment Between the Question, Scope, Evidence, and Method

The selected method should undergo final alignment validation before search planning or other operational choices are fixed.

Validation checks whether the method remains coherent with the research question, review purpose, scope, evidence characteristics, rigour, feasibility, and intended review output.

• Research question: Does the selected method support the kind of answer the research question requires? A no or needs-revision result requires reconsidering the method or refining the question before proceeding.
• Review purpose: Does the method support the intended review purpose without changing the function of the review? A no or needs-revision result requires revising the method choice or review design.
• Scope: Is the method compatible with the defined breadth, depth, and boundaries of the review? A no or needs-revision result requires reconsidering the scope or selected method.
• Evidence characteristics: Can the method accommodate the forms, diversity, and synthesis demands of the evidence to be reviewed? A no or needs-revision result requires reassessing evidence fit before execution.
• Rigour and transparency: Can the method support the rigour, documentation, and transparency required for the intended claims? A no or needs-revision result requires reconsideration before proceeding.
• Feasibility: Can the method be executed credibly within practical constraints without undermining methodological fit? A no or needs-revision result requires revising scope, timeline, resources, or the execution plan.
• Intended review output: Will the method produce the form of synthesis or review output required by the project? A no or needs-revision result requires reconsidering the method before operational planning.
• Overall coherence: Do the research question, review purpose, scope, evidence characteristics, rigour, feasibility, and intended review output remain mutually consistent with the selected method? A no or needs-revision result requires resolving the contradiction before progression.

Any no or needs-revision result indicates that the method or review design should be reconsidered before operational choices are locked in.

Once alignment is satisfactory, the selected method is ready to guide the literature review search strategy and subsequent planning.

This final verification keeps later execution anchored to a defensible and internally coherent method choice.