No, a feasibility study does not typically require a control group. The primary purpose of a feasibility study is to assess the practicality and viability of an intervention, program, or research design, rather than to determine its effectiveness or compare it against an alternative.
The Core Purpose of Feasibility Studies
Feasibility studies are crucial preliminary steps in the research process, especially before embarking on a larger, more expensive randomized controlled trial (RCT). They are designed to answer questions about the doability of a study or intervention. Key aspects assessed include:
- Recruitment and Retention Rates: Can enough participants be recruited and retained for the duration of the study?
- Intervention Fidelity: Can the intervention be delivered consistently and as intended?
- Acceptability and Adherence: Is the intervention acceptable to participants, and will they adhere to it?
- Data Collection Methods: Are the proposed data collection tools and procedures practical and reliable?
- Resource Requirements: What resources (staff, budget, time) are needed?
- Potential Challenges: Identifying unforeseen practical or logistical hurdles.
Unlike efficacy trials, which often use control groups for comparison, feasibility studies primarily focus on process-related outcomes. In fact, design elements such as randomization or the inclusion of a control group have not been found to be distinguishing features separating studies labeled as 'feasibility' from those labeled as 'pilot' by investigators. This underscores that their presence is not a defining characteristic or necessity for a study to be considered feasible.
When Control Groups Are Essential (and When They're Not)
Control groups are fundamental components of study designs aimed at establishing causality or determining the effectiveness of an intervention. This is where randomized controlled trials (RCTs) shine. In an RCT, participants are randomly assigned to either an intervention group or a control group (receiving a placebo, standard care, or no intervention) to minimize bias and ensure that any observed differences in outcomes can be attributed to the intervention.
| Feature | Feasibility Study | Efficacy/Effectiveness Study (e.g., RCT) |
|---|---|---|
| Main Objective | Assess viability, practicality, and design elements | Determine intervention effectiveness and causality |
| Control Group | Not typically required | Essential for comparison and valid conclusions |
| Primary Outcomes | Process-related (e.g., recruitment rate, adherence, data completeness) | Clinical or impact-related (e.g., symptom reduction, disease progression) |
| Sample Size | Generally small | Larger, calculated to detect meaningful differences |
| Focus | Can we do this? | Does this work? |
For a feasibility study, the focus is on whether the research itself is possible and practical to conduct on a larger scale. The absence of a control group does not diminish its value because its aims are different from those of an efficacy trial.
Practical Insights
While a control group is not a requirement for a feasibility study, there might be scenarios where elements resembling a comparison could exist, but their purpose would still be about feasibility rather than comparative effectiveness. For instance:
- Testing different recruitment strategies: A feasibility study might test two different recruitment methods to see which is more effective at enrolling participants, without aiming to compare intervention outcomes.
- Assessing data collection tools across sites: A study might test a new questionnaire at two different clinics to see if it's feasible to administer in various settings.
In these cases, the "comparison" is for operational efficiency or design optimization, not for evaluating the intervention's impact. The key takeaway remains that a feasibility study's core purpose dictates its design, and that purpose rarely necessitates a control group for comparative outcome analysis.
