Search interfaces are evaluated based on usability:
- Effectiveness
- Efficiency
- Satisfaction

Evaluation of Search Interfaces

One major usability design flaw is when users cannot find content when making searches for basic material or when it isn’t easily accessible to mission-critical pages, this is a result of the site having low findability and discoverability. 

- Findability: Users are able to efficiently locate content or functionality in an application or website that they presume exists.


- Discoverability: Users come across unfamiliar content or functionality without knowing beforehand. 

Findability vs Discoverability

A Mental model is what the user understands about the user system. It is one of the more significant concepts in human-computer interaction (HCI).

Mental Models

- Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
- Efficiency: Once users have learned the design, how quickly can they perform tasks?
- Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
- Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
- Satisfaction: How pleasant is it to use the design?

Rutgers University

Usability is a quality attribute that assesses how easy user interfaces are to use. The word "usability" also refers to methods for improving ease-of-use during the design process.

Definition of Utility = whether it provides the features you need.
Definition of Usability = how easy & pleasant these features are to use.
Definition of Useful = usability + utility.

Usability

Components of Usability

10 general principles for interaction design outlined by Jakob Nielson. Called "heuristics" because they are broad rules of thumb and not specific guidelines.

Nielson's 10 Usability Heuristics

- Usability-Lab Studies: participants are brought into a lab, one-on-one with a researcher, and given a set of scenarios that lead to tasks and usage of specific interest within a product or service.

- Eye tracking: an eye tracking device is configured to precisely measure where participants look as they perform tasks or interact naturally with websites, applications, physical products, or environments.

- Usability Benchmarking: tightly scripted usability studies are performed with several participants, using precise and predetermined measures of performance.

- Unmoderated Remote Panel Studies: a panel of trained participants who have video recording and data collection software installed on their own personal devices uses a website or product while thinking aloud, having their experience recorded for immediate playback and analysis by the researcher or company.

- Moderated Remote Usability Studies: usability studies conducted remotely with the use of tools such as screen-sharing software and remote-control capabilities.

- Desirability Studies: participants are offered different visual-design alternatives and are expected to associate each alternative with a set of attributes selected from a closed list; these studies can be both qualitative and quantitative.

- Card Sorting: a quantitative or qualitative method that asks users to organize items into groups and assign categories to each group. This method helps create or refine the information architecture of a site by exposing users’ mental models.

- A/B Testing (related to “multivariate testing,” “live testing,” or “bucket testing”): a method of scientifically testing different designs on a site by randomly assigning groups of users to interact with each of the different designs and measuring the effect of these assignments on user behavior.


Usability Methods

Users are accompanied one-on-one with a researcher in a lab setting, and are told to complete tasks on a product or service.

Learn Before

Related

Learn After