Systematic Reviews – Questions, Methods and Usage

Table 5. Classification of types and questions commonly addressed by systematic reviews
Focused Classification of questions and systematic review types Characteristic questions Examples of possible synthesis methods

Effect-driven (impact)question

  • Questions concerned with impact of different interventions

Explanatory (causal)

  • Questions concerned with why and how events occur


  • Questions abouteconomic impact
What is the effect of this treatmentor intervention?
What is the difference in the effect of two or more competing interventions?
What is the effect of this complex intervention?
What is the effect of this approach to social policy in this context?

What is the accuracy of this diagnostic tool?
What is the cause of a specific phenomenon?
What are the sources of variation between two groups, conditions or states?
How and why the outcomes between groups differ?
What is the cost of this intervention?
Statistical meta-analysis of experimental trials
Statistical meta-analysis of experimental trials

Multi-component mixed methods reviews
Realist synthesis of evidence of efficacy and relevance across different policy areas
Meta-analysis of evaluations of diagnostic tests
Statistical meta-analysis

Statistical meta-analysis

Statistical meta-analysis or qualitative meta-synthesis
Synthesis of cost-benefit analyses

Hermeneutic (interpretative and/or descriptive)

  • Questions aiming to interpret, describe, summarize and present data, events and observations
What is the meaning of a specific phenomenon?
What is the process of a specific action, phenomenon or event?
What are the attributes of this intervention or activity?

Is this complex intervention appropriate?
Critical interpretative synthesis of ethnographic studies
Conceptual synthesis such as metaethnography
Framework synthesis framed by dimensions explicitly linked to
particular perspectives
Multi-component mixed methods reviews


  • Questions aiming to determine effect and interpret phenomena
What is the impact of an intervention and what are the participants’ views and experiences of participating in the intervention? Multi-component mixed methods reviews such as meta-analysis alongside the thematic narrative synthesis