Research Guides: Evidence Synthesis: 1. Draft your Research Question

Developing a Research Question

Developing your research question is one of the most important steps in the evidence synthesis process. At this stage in the process, you and your team have identified a knowledge gap in your field and are aiming to answer a specific question:

If X is prescribed, then Y will happen to patients?

OR assess an intervention:

How does X affect Y?

OR synthesize the existing evidence

What is the nature of X?

Whatever your aim, formulating a clear, well-defined research question of appropriate scope is key to a successful evidence synthesis. The research question will be the foundation of your synthesis and from it your research team will identify 2-5 possible search concepts. These search concepts will later be used in step 6 to build your search strategy.

Search Concepts

Formulating a research question takes time and your team may go through different versions until settling on the right research question. To help formulate your research question, some research question frameworks are listed below (there are dozen of different types of these frameworks--for a comprehensive overview, see this guide from the University of Maryland)

Think of these frameworks as you would for a house or building. A framework is there to provide support and to be a scaffold for the rest of the structure. In the same way, a research question framework can also help structure your evidence synthesis question. Probably the most common framework is PICO:

PICO for Quantitative Studies

P Population/Problem
I Intervention/Exposure
C Comparison
O Outcome

Example: Is gabapentin (intervention), compared to placebo (comparison), effective in decreasing pain symptoms (outcome) in middle aged male amputees suffering phantom limb pain (population)?

While PICO is a helpful framework for clinical research questions, it may not be the best choice for other types of research questions, especially outside the health sciences. Here are a few others (for a comprehensive, but concise, overview of the almost 40 different types of research question frameworks, see this review from the British Medical Journal: Rapid review of existing question formulation frameworks)

PICo for Qualitative Studies

P Population/Problem
I Phenomenon of Interest
Co Context

Example: What are the experiences (phenomenon of interest) of caregivers providing home based care to patients with Alzheimer's disease (population) in Australia (context)?

SPICE

S Setting
P Perspective (for whom)
I Intervention/Exposure
C Comparison
E Evaluation

Example: What are the benefits (evaluation) of a doula (intervention) for low income mothers (perspective) in the developed world (setting) compared to no support (comparison)?

SPIDER

S Sample
PI Phenomenon of Interest
D Design
E Evaluation
R Study Type

Example: What are the experiences (evaluation) of women (sample) undergoing IVF treatment (phenomenon of interest) as assessed?

Design: questionnaire or survey or interview

Study Type: qualitative or mixed method

Inclusion/Exclusion Criteria

Inclusion Criteria

Identify the criteria that will be used to determine which research studies will be included. The inclusion and exclusion criteria must be decided before you start the review. Inclusion criteria is everything a study must have to be included. Exclusion criteria are the factors that would make a study ineligible to be included. Criteria that should be considered include:

Type of studies: It is important to select articles with an appropriate study design for the research question. Dates for the studies and a timeline of the problem/issue being examined may need to be identified.

Type of participants: Identify the target population characteristics. It is important to define the target population's age, sex/gender, diagnosis, as well as any other relevant factors.

Types of intervention: Describe the intervention being investigated. Consider whether to include interventions carried out globally or just in the United States. Eligibility criteria for interventions should include things such as the dose, delivery method, and duration of the investigated intervention. The interventions that are to be excluded may also need to be described here.

Types of outcome measures: Outcome measures usually refer to measurable outcomes or ‘clinical changes in health’. For example, these could include body structures and functions like pain and fatigue, activities as in functional abilities, and participation or quality of life questionnaires.

For additional information see Chapter 3 of the Cochrane Handbook for Systematic Reviews of Interventions: Chapter 3 Defining the criteria for including studies and how they will be grouped for the synthesis

Exclusion Criteria

A balance of specific inclusion and exclusion criteria is paramount. For some systematic reviews, there may already be a large pre-existing body of literature. The search strategy may retrieve thousands of results that must be screened. Having explicit exclusion criteria from the beginning allows those conducting the screening process, an efficient workflow. For the final product there should be a section in the review dedicated to 'Characteristics of excluded studies.' It is important to summarize why studies were excluded, especially if to a reader the study would appear to be eligible for the systematic review.

For example, a team is conducting a systematic review regarding intervention options for the treatment of opioid addiction. The research team may want to exclude studies that also involve alcohol addiction to isolate the conditions for treatment interventions solely for opioid addiction.

Common Inclusion/Exclusion Criteria

Inclusion and exclusion criteria set the boundaries for the systematic review. They are determined after setting the research question usually before the search is conducted, however scoping searches may need to be undertaken to determine appropriate criteria. Many different factors can be used as inclusion or exclusion criteria. Information about the inclusion and exclusion criteria is usually recorded as a paragraph or table within the methods section of the systematic review. It may also be necessary to give the definitions, and source of the definition, used for particular concepts in the research question (e.g. adolescence, depression).

Other inclusion/exclusion criteria can include the sample size, method of sampling or availability of a relevant comparison group in the study. Where a single study is reported across multiple papers the findings from the papers may be merged or only the latest data may be included.

From The University of Melbourne Libguide

Video: Evidence Synthesis Institute: Formulating a Research Question

From umn Libraries (4:42 minutes)

Evidence Synthesis