Which of the following is the correct distinction between formative and summative usability evaluation?

The primary distinction between formative and summative usability evaluation lies in their goals and timing within the development lifecycle. Formative evaluation is conducted during the design and development process. Its main purpose is to identify usability issues and provide feedback to "form" or improve the product. In contrast, summative evaluation is typically performed at the end of a development cycle on a finished or near-finished product. Its goal is to "sum up" or assess the overall usability, often by measuring it against predefined benchmarks or competitors, thereby judging the final outcome.

A. This option incorrectly reverses the definitions. Formative evaluations focus on improvement, while summative evaluations assess the final outcome.
B. This is an incorrect generalization. Both evaluation types can use either experts or users; the choice of participants is method-dependent, not type-dependent.
D. This is also an incorrect generalization. For instance, formative evaluations frequently use informal user tests, while summative evaluations can employ expert-based methods. ---

1. ISTQB® Certified Tester Usability Testing Syllabus (Version 1.0, 2018).

Section 3.2.1, Formative Evaluation: "The main goal of a formative evaluation is to find usability problems in a product and to get recommendations for the improvement of the product." (p. 20)

Section 3.2.2, Summative Evaluation: "The main goal of a summative evaluation is to assess the level of usability of a product. A summative evaluation is often used to determine if a product meets its usability goals..." (p. 21)

These sections directly support that formative evaluation is for improvement and summative evaluation is for assessment of the outcome.

2. Preece, J., Rogers, Y., & Sharp, H. (2019). Interaction Design: Beyond Human-Computer Interaction (5th ed.). Wiley.

Chapter 13, Evaluation Studies: From Controlled to Natural Settings: The text distinguishes between the two by stating, "Formative evaluations are done to help designers improve a design... Summative evaluations are done to assess the quality of a finished product." (p. 418). This aligns perfectly with the correct answer.

3. Sauro, J., & Lewis, J. R. (2016). Quantifying the User Experience: Practical Statistics for User Research (2nd ed.). Morgan Kaufmann.

Chapter 1, Introduction: The authors define the terms: "Formative evaluations are done as part of an iterative design process... The goal of a formative evaluation is to find and fix problems. In contrast, the goal of a summative evaluation is to describe the user experience of a finished product..." (p. 6). This confirms that formative focuses on improvement ("fix problems") and summative on assessment ("describe the user experience of a finished product"). DOI: https://doi.org/10.1016/C2014-0-03229-9