Definition
Formative and summative evaluation represent two distinct purposes for conducting evaluation, differentiated primarily by timing and intended use.
Formative evaluation occurs during programme implementation and is designed to improve the programme while it is running. It asks: "How can we make this work better?" Findings feed directly into adaptive management decisions, allowing implementers to adjust activities, refine approaches, and address challenges in real time.
Summative evaluation occurs after a programme has reached a stable state or completed implementation, and is designed to judge overall merit, worth, or impact. It asks: "Did this work, and should it continue, scale, or end?" Findings inform accountability decisions, funding continuation, and strategic choices about programme replication or termination.
The distinction matters because each type requires different design choices: formative evaluation prioritizes speed and actionable feedback, while summative evaluation prioritizes rigor and defensible conclusions.
Why It Matters
Understanding the formative-summative distinction is fundamental to evaluation design for three reasons:
First, it determines evaluation timing. Conducting a summative evaluation too early, before a programme has stabilized, produces unreliable findings about effectiveness. Conversely, waiting for summative judgement when formative feedback is needed means missing opportunities for improvement.
Second, it shapes stakeholder engagement. Formative evaluation typically involves implementers as co-learners, creating psychological safety for honest assessment. Summative evaluation often positions evaluators as external judges, requiring more formal protocols and potentially different stakeholder dynamics.
Third, it affects resource allocation. Formative evaluation can be lighter-weight and iterative, while summative evaluation typically demands more rigorous design, larger samples, and more extensive analysis. Understanding the purpose helps justify the appropriate level of investment.
In Practice
Most robust evaluation plans include both formative and summative components, sequenced appropriately:
Formative evaluation appears as:
- Mid-term reviews that identify implementation bottlenecks
- Rapid feedback loops after major programme activities
- Process evaluations that examine fidelity and adaptation
- Developmental evaluation in complex adaptive programmes, where the evaluator works alongside implementers to navigate uncertainty
Summative evaluation appears as:
- Endline evaluations conducted at programme completion
- Impact evaluations with rigorous counterfactual analysis
- Meta-evaluations that synthesize findings across multiple programmes
- Performance evaluations that judge value for money and sustainability
A well-designed evaluation plan specifies which questions are formative (for improvement) versus summative (for judgement), and aligns methods accordingly. Formative questions might ask "What barriers prevented target groups from accessing services?" Summative questions ask "Did the programme achieve its intended outcomes compared to a counterfactual?"
Related Topics
- Evaluation Terms of Reference, Specifies evaluation purpose, including formative vs summative intent
- Evaluation Matrix, Maps evaluation questions to methods, timing, and use
- Evaluation Use, Maximizes formative findings for programme improvement
- Programme Improvement, How evaluation feeds adaptive management
- Accountability Evaluation, Summative judgement for donors and stakeholders
- Developmental Evaluation, Formative approach for complex, adaptive contexts