Glossary

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Psychometric Evaluation(also: Psychometric Validation, Psychometric Analysis)

The process of assessing whether a measurement instrument (such as a questionnaire or survey) possesses desirable statistical properties including validity, reliability, and consistency. In accessibility and usability research, psychometric evaluation is used to determine…

Quality of Perception(also: QoP)

An evaluation framework from the multimedia-accessibility research literature for measuring how well a user can understand and use a media presentation, combining objective comprehension metrics (e.g., fact-recall or multiple-choice quiz accuracy) with subjective judgements…

SARI(also: System output Against References and against the Input sentence)

An automatic evaluation metric for text simplification systems that compares a system’s output against both the original input sentence and a set of human-written simplification references, rewarding the system for adding appropriate words, keeping important words, and deleting…

SHAP(also: SHapley Additive exPlanations)

A unified framework for feature-importance explanations of machine-learning models, introduced by Lundberg and Lee in 2017, grounded in Shapley values from cooperative game theory. For any model and input, SHAP assigns each feature a value representing its contribution to that…

SUMI(also: Software Usability Measurement Inventory)

A standardised questionnaire-based method for measuring software usability from the end user perspective. SUMI assesses five dimensions: efficiency, affect (user satisfaction), helpfulness, control, and learnability. In accessibility contexts, SUMI can be adapted alongside…

Scenario-Based Evaluation(also: Path-Based Testing, User Journey Testing)

An accessibility evaluation approach that assesses the complete user experience across a sequence of steps needed to accomplish a task, rather than testing individual pages in isolation. For example, evaluating an e-commerce checkout means testing every step from product search…

Score Prediction(also: Predicted grade, Comprehension self-prediction)

A subjective-response evaluation item in which a research participant, immediately after reading a passage and before learning their actual comprehension-question score, estimates the percentage of questions they will have answered correctly. Score prediction is used in…

Self-Assessment Manikin(also: SAM)

A nonverbal pictorial instrument developed by Bradley and Lang (1994) for measuring the affective dimensions of valence, arousal, and dominance. Respondents select from a row of stylised manikin figures whose expressions and body states vary along each dimension, typically on a…

Semi-Automatic Evaluation(also: Semi-Automated Testing, Guided Manual Evaluation)

An approach to accessibility evaluation that combines automated checks with human expert judgment. Semi-automatic tools run algorithmic tests to detect issues that can be identified programmatically — such as missing alt text or invalid ARIA attributes — and then guide the…

Semiotic Inspection Method(also: SIM, MIS)

An evaluation method from Semiotic Engineering theory that systematically assesses the communicability of an interactive system by examining how well the designer's intended message is conveyed through the interface. The evaluator analyzes three types of interface signs…

Sensitivity(also: Recall, Thoroughness, Completeness)

In the context of accessibility evaluation, sensitivity (also called recall or thoroughness) is the proportion of true accessibility problems that are successfully identified and reported by an evaluator. High sensitivity means that most real barriers are found, while low…

Signal Detection Theory(also: SDT)

A statistical framework used to measure the accuracy of a system or person in distinguishing between the presence and absence of a target signal amid noise. In accessibility and assistive technology research, Signal Detection Theory is used to evaluate how well detection systems…

Single Case Experimental Design(also: SCED, Single Subject Design, N-of-1 Design)

A research methodology in which individual participants serve as their own control, with repeated measurements taken during baseline and intervention phases to evaluate the effect of a treatment or intervention. This approach is particularly valuable in accessibility and…

Structured Walkthrough(also: Guided Walkthrough, Accessibility Walkthrough)

An accessibility evaluation method in which an evaluator is guided through a systematic series of checks using predefined steps, instructions, and heuristics. Unlike a full WCAG conformance review which requires expert knowledge to interpret success criteria, a structured…

Testability(also: Reliably Human Testable, Machine Testable)

In the context of accessibility standards, testability refers to the degree to which a guideline or success criterion can be evaluated with consistent, reproducible results — either through automated tools (machine testable) or through human inspection where at least 80% of…

Theory of Change(also: ToC, Logic Model)

An explicit articulation of how and why a planned intervention is expected to produce its intended outcomes - typically expressed as a chain linking inputs to activities, outputs, short- and long-term outcomes, and the assumptions connecting each step. A theory of change makes…

Trust in Automation(also: Automation trust, TiA)

A human factors construct describing the extent to which a person believes an automated system — a car, aircraft, medical device, AI assistant, or robot — will perform reliably and behave in their interest, typically measured via validated questionnaires such as the Trust in…

UEQ-S(also: User Experience Questionnaire - Short, Short UEQ)

UEQ-S is an eight-item short version of the User Experience Questionnaire, a standardised survey instrument that measures subjective user experience on a 7-point semantic-differential scale. It captures two broad factors: pragmatic quality (supportive, easy, efficient, clear)…

Unified Web Evaluation Methodology(also: UWEM)

A standardized methodology developed by the European Web Accessibility Benchmarking Cluster (WAB Cluster) for evaluating the accessibility of websites in a consistent, comparable way. UWEM provides formulas for calculating quantitative accessibility scores from WCAG checkpoint…

Usability Heuristics(also: Nielsen's Heuristics, Nielsen Heuristics, 10 Usability Heuristics)

A set of ten general principles for user interface design developed by Jakob Nielsen (originally with Rolf Molich in 1990, refined in 1994): visibility of system status, match between system and the real world, user control and freedom, consistency and standards, error…

User Engagement Scale(also: UES, UES-SF)

A validated self-report questionnaire for measuring user engagement with digital systems across dimensions including focused attention, perceived usability, aesthetic appeal, and reward. Developed by O'Brien and Toms and later shortened to the 12-item UES Short Form (UES-SF),…

User Experience Questionnaire(also: UEQ, UEQ-S, Short UEQ)

A standardised self-report instrument, developed by Schrepp and colleagues, that captures a user's subjective impression of a product across dimensions such as attractiveness, efficiency, perspicuity, dependability, stimulation, and novelty via pairs of contrasting adjectives…

Video Coding(also: Behavioural Video Coding, Video Data Coding)

A systematic research method in which trained analysts review video recordings to identify, label, and categorise specific behaviours, actions, emotions, or events. In accessibility and usability research, video coding is used to analyse recordings of user testing sessions to…

Violation Severity(also: Accessibility Violation Severity, Barrier Severity)

A measure of how significantly an accessibility violation impacts users with disabilities, typically rated on a scale from no violation to critical barrier. In accessibility evaluation, violation severity helps prioritize remediation efforts by distinguishing between minor…

Wilcoxon Signed-Rank Test(also: Wilcoxon Test)

The Wilcoxon signed-rank test is a non-parametric alternative to the paired t-test, used to compare two related samples when the data are ordinal or not normally distributed. It ranks the absolute differences between paired observations and tests whether the sum of positive and…

Wizard-of-Oz Study(also: Wizard of Oz, WoZ Study, Wizard-of-Oz Method)

A Wizard-of-Oz study is a research method in human-computer interaction where participants interact with a system they believe is autonomous, but which is actually being partially or fully operated by a human researcher (the "wizard") behind the scenes. This technique is…