CIS 443 Final Review

7.17 What are "within-subject" and "between-subject" designs? What are the benefits and drawbacks of each?

Within-subject designs are where all participants see all conditions. - Pros: higher sample size = better external validity - Cons: can decrease internal validity if factors such as learning bias and transfer of knowledge come into play. Between-subject designs are where different groups see different conditions. - Pros: eliminate factors such as learning bias if participants experiencing one condition can effect the results of another condition. - Cons: result in smaller sample sizes = worse external validity

7.18 Why do psychology experiments explain (a) how participants were recruited, (b) the instructions that they received, and (c) how they were compensated for their time in the experiment?

(a) essential as it shows how participant demographics may differ from target users (b) shows if any bias was introduced through how the instructions were given (also if each participant were given the same instructions) (c) compensation will show how participants were motivated during the study; were they primarily focused on getting through as fast as possible, or were making sure they were getting their answer right?

7.22 What is "informed consent"? What must be commmunicated when getting informed consent?

- Permission granted in the knowledge of the possible conseqeuences. - Must be communicated that results will remain confidential and that the participant may quit the experiment at any time without penalty.

1.9. What was Card, Moran, and Newell's noted contribution to human-computer interaction? Why was this an important contribution? (pp.11-12)

- an early HCI project called GOMS advanced human performance testing, b/c it addressed the mental activities that guide behavior

2.2. Work can be characterized as having three dimensions: activities, artifacts, and social context. Describe each of these. Why is it important to consider each in the design of a user interface? (pp.38-39)

1. Activities - The personal goals, activities to achieve them. 2. Artifacts - The physical objects used to carry out the activities. 3. Social context - The people their relationships, motivations. - Important b/c all three have an effect on how a UI will be used.

Name the three steps (and their sub-steps) of the scenario-based framework used in the textbook.

1. Analyze - Problem scenarios 2. Design - Activity scenarios - Information scenarios - Interaction scenarios 3. Prototype and evaluate - Usability specifications

What are the 3 concepts contributing to the general concept of usability?

1. Human performance, time, and errors 2. Human cognition, mental models of plans and actions 3. Collaboration, group dynamics, and workplace context

What are the questions to ask during a cognitive walkthrough evaluating a system's interaction design?

1. Will the user know the correct subgoal or subtask? Example: Print or select printer first? 2. Will the user know that the correct action is available? Example: Any clues for how to print? 3. Will the user associate the correct action with the subgoal? E.g.: Type "lp" or find in menu? 4. If the correct action is performed, will the user know that progress is being made toward the goal? Example: Is it being printed?

7.16 Why do you want your participants to maintain a 97% accuracy? Explain using a graph.

97% accuracy is right around where the speed-accuracy tradeoff graph plateaus when going from chance accuracy to maximum and fast reaction time to slow. The average reaction time greatly increase when trying to attain accuracy levels higher than 97%.

7.12 A study reports that people complete tasks faster with interface A than with interface B. The study presents accurate statistics that show the difference is real. Is A better than B? Explain.

Again, looking at the speed-accuracy tradeoff, because we do know the accuracy of either the interfaces in this case, we cannot conclude that one interface is better than the other. That can only occur if an interface has better speed AND accuracy.

7.15 in an experiment, how do you get people to quickly as possible while maintaining 97% accuracy?

An experimental design should facilitate user motivation in a way that speed and accuracy are appropriately incentivized. - e.g. for an activity that typically takes 5 minutes, $20 for the correct answer and an additional $1 for every 5 seconds under 5 minutes

H.6. What is the value in carrying out an HTA as opposed to simply listing the sequence of steps that a person needs to take to accomplish a task, such as in a flowchart?

Because, although simple tasks can be defined by a string of actions, complex tasks can be accomplished by many different ways. It is thus important to cluster subsets of actions into meaningful groups that represent subsets of actions that are closely related to each other because they relate to a single subgoal within the hierarchy. It is not only important to know what is the sequence of actions that a person takes, but also why a person takes (or would take) such a set of actions.

6.4 What is the value in generating numerous designs that do not get implemented?

Each design considers alterative components/ideas, and understanding why those designs DON'T work is as important as understanding why a design DOES work.

What is ease of use? (7)

Ease of use is a measure of how well a system supports users accomplishing tasks.

6.3.1 What is a high-fidelity prototype, and its advantages and disadvantages?

Highly detailed and often expensive prototypes - Pros: closely represents actual product - Cons: may mislead clients to think certain aspects are completed, cause premature commitment to design ideas, more expensive (money/time)

K.3 How is human vision like a flashlight?

Human's have high resolution vision in only a tiny area at the center of their vision. Therefore, for most visual processes, humans must aim that area at what they want to process. This is similar to using a flashlight in a dark room and repeatedly processing small areas of interest.

7.10 What are common independent and dependent variables in a user observation study?

Independent: the UI layouts (button-scheme, highlighted colors, etc.), types of feedback Dependent: speed, accuracy, overall success-rate

What is stimulus-response compatiblity?

Is a measure of the speed and accuracy with which a person can learn, execute, and retain knowledge of the mappings between stimuli and responses. Such as, the mappings between four lights and four buttons.

F.1. What is Fitts' Law?

Is a predictive model of human movement primarily used in human-computer interaction and ergonomics.

What is a problem scenario?

Is a story about a problem domain as it exists prior to the introduction of new digital technology.

2.5. What is ethnography? (pp. 41-42)

Is an analytical technique in which the analyst becomes intensely involved in a group's activities as a participant/observer, and collects data about that group, to understand it from the inside out. A debate: Can the ethnographer start with a hypothesis, or must the hypotheses be data-driven? Are they scientists?

F.5. How is Fitts' useful?

It provides a basis for comparing the efficiency of different pointing devices or pointing techniques. i.e. provides way to collect quantitative data, which is important for scientific research.

5.3. What is the "gulf of execution"?

It refers to the difficulty that people have in determining the physical actions needed to accomplish a task with an interface.

7.11 You present a user with two interfaces, A and B. The user takes 32 sec to do a task using A and 98 sec to do the same task using B. Which interface is better? Explain your answer.

Looking at the speed-accuracy tradeoff, because we do know the accuracy of either the interfaces in this case, we cannot conclude that one interface is better than the other. That can only occur if an interface has better speed AND accuracy.

2.6. Why is it important to get all stakeholders involved in the requirements analysis phase of a system design? (pp. 43-44)

No stakeholder can adequately communicate the perspective of others; therefore important to directly talk to all.

7.1 What is the best way to test the usability of a user interface?

Observe and conduct studies with real users doing real tasks.

7.3.2 What is empirical evaluation, and its advantages and disadvantages?

Observing real users doing real tasks; follows pattern of a psychological experiment - Pros: most accurate in replicating how users will interact w/system in real life, - Cons: slow/expensive, does not always reveal why better or worse

H.4. What are the three common types of plans discussed in the reading?

Procedures, selective rules, and time-sharing tasks.

6.3.2 What is a low-fidelity prototype, and its advantages and disadvantages?

Simple and often inexpensive prototypes (easy as sketch on napkin) - Pros: more likely to generate ideas (Wendy Marsh Intel), roughness conveys that design ideas are tentative, cheap (money/time) - Cons: further from actual product, may be hard for customers to make certain connections; certain situation requires high-fidelity prototypes

7.3.1 What is analytical evaluation, and its advantages and disadvantages?

Studying or modeling the interface without users - Pros: cheaper/faster, can help to show what is wrong - Cons: not the most accurate way to evaluate UI's

F.3. What is the equation?

T = a + b log2 (D/S + 1) a, b = constants (empirically derived) D = distance S = size ID is Index of Difficulty = log2(D/S+1)

K.4 How does Fitts' law predict the apparent ease of hitting the edge of a display with the mouse cursor?

The edge of a display is a relatively easy target to hit as it has an infinite size going away from the screen. Plugging in an inifinite size into the Fitts' law equation will make it apparent that it results in a small time.

K.1 Why do the eyeballs rotate in their sockets? In other words, why do people move their eyes?

The eyes rotate in their sockets to orient high-resolution vision towards items of interest.

K.5 Explain, in terms of human information processing, the benefit of physical keyboards over touchscreen keyboards.

The problem with digital technology: - Systems can be complicated and provide no affordances. (?)

7.21 How do you quantitatively measure the validity of an experiment?

You CANNOT quantitatively measure the validity of an experiment.

Write the code necessary to set up a Tkinter GUI with three labels. (project 3, 4)

from tkinter import * def main(): root = Tk() frame1 = Frame(root) frame1.pack(side=TOP) label1 = Label(frame1, text="1", width=10) label2 = Label(frame1, text="2", width=10) label3 = Label(frame1, text="3", width=10) label1.pack(side=LEFT) label2.pack(side=LEFT) label3.pack(side=LEFT) main()

Write the code necessary to play a sample sound. (project 1)

import sound def main(): sample_sound = "path/to/sound/file.wav" sound.Play(sample_sound) main()

What are the ten guidelines for interaction design?

• Use simple and natural dialog. • Speak the users' language. • Minimize memory load. • Be consistent. • Provide feedback. • Provide clearly marked exits. • Provide shortcuts. • Provide good error messages. • Prevent errors. • Include good help and documentation

H.7. How is HTA useful for building easy-to-use, easy-to-learn, and useful computer systems?

- "HTA differs radically from earlier methods of analysis by beginning, not with a list of activities, but by identifying the goals of the task." - "In routine repetitive tasks, actions vary little.... In complex tasks, the same goals may be pursued by different routes and different means, depending on circumstances peculiar to each occasion. Hence, simply to list actions without understanding what they are for can be misleading. Complex systems are designed with goals in mind, and understanding how a system attains or fails to attain its designated goal is the primary purpose of the analysis."

H.2. What is a task?

- A portion of an activity that is defined by a common goal (sub-goal)

6.1 What is a prototype? What is a user interface prototype?

- A prototype is a concrete but partial implementation of a system - Can evaluate diff aspects of a system design such as speed, component interconnection, usability with a user interface prototype

What is a cognitive walkthrough? (7)

- A usability inspection method. - Slightly biased towards ease of learning - Good for: "walk up and use" software - Relates to cycle of human info processing

11. What is a user interaction "mode"? Are modes generally considered to be a good or bad idea in user interface design? Why? Give two examples of when an interaction mode would be a good design decision and explain why.

- Are restricted interaction states in which only certain actions are possible. Such as a "modal" dialog box that requires a response before you can do anything else with your computer. - In general, should be avoided in UI design.

What is a tradeoff?

- Are the alternatives, and the benefits and problems associated with each alternative. They exist throughout a design process. For example: nail down a design, or keep your options open.

5.5. What is a command language interface? (pp. 161-163)

- Command line interface consists of a console with a simple input location where a user can enter their commands.

5.3. How can an interface reduce these two "gulfs"?

- Direct manipulation thought to reduce gulf of execution

2.11. In scenario-based design, a "claims analysis" is a consideration of design tradeoffs, a sort of cost-benefit analysis. Why is a consideration of design tradeoffs important in a design activity? (pp. 72-75)

- Elaborate scenarios, explaining how/why particular feature is having range of impacts on actors - Documents why one/more scenarios were written, by isolating most important features of the narratives - Extend scenarios, creating possible ties w/others - Promotes balanced view of situations (+/-) - Motivate design reasoning

1.4. What is iterative development? Why is iterative development a critical component of interface design? (p.9)

- Focuses on looping thru: *req. analysis->design->prototyping->evaluating* as a means of developing and refining a system design. - (i.e) A process in which designs and design documents are produced as an output of each phase in the design process, but continually modified through prototyping and testing.

7.2 What is the difference between formative and summative evaluation?

- Formative evaluation: takes place during design process -- how are we doing? - Summative evaluation: takes place after the design process -- how did we do?

2.4. Which of the three dimensions of work are best captured by HTA? Which are not so well captured by HTA?

- HTA often does not capture the emotional aspects of a task or experience, the important social relationships, the motivations, the psychological experiences. - The artifacts may be mentioned in passing, but are not necessarily directly covered. - It captures the activities very well.

2.10. What are hypothetical stakeholders? (Note: They are also known as personas.) Why is the role of hypothetical stakeholders in a design process? (pp. 66-67)

- Imaginary people with characteristics you think are typical of a stakeholder group. - Serve as actors in the problem scenarios, and the background and motivation for each helps us to imagine how a specific scenario might unfold from that person's perspective.

2.9. When interviewing a user or potential user of a system, why is it sometimes useful to start the interview with open-ended questions? What is an example of an open-ended question? An example of a question that is not open-ended?

- Interviews are stressful, and open-ended/easy questions are a good way of making situation more comfortable. - Opens up topics that interviewer could ask about in more detail. - Why do you enjoy participating and attending science fairs?

1.3. What is a prototype? How are prototypes used in the design and development of user interfaces? (p.8)

- Is a concrete but partial implementation of a system design (p.198). It converts abstract ideas into concrete examples. In system design, they must somehow capture the dynamic aspect of the system. - (i.e.) an operational model to demonstrate a design idea.

2.8. What is a field study? What is the goal of a field study? What kinds of data should you collect in a field study? What kinds of analyses would be useful to conduct? (pp. 51-64)

- Is a general method for collecting data about users, user needs, and product requirements that involves observation and interviewing. Data are collected about task flows, inefficiencies, and the organizational and physical environments of users.

1.8. What is usability? How can it be measured quantitatively? (pp.9-11)

- Is a measure of a system in terms of ease of use, ease of learning, and user satisfaction. (It is also a "software quality" such as reliability, portability, maintainability, security,...)

5.9. What is a storyboard? (p.190) What aspect of a user interface does a storyboard help to convey?

- Is an event-by-event pictoral-based description of a sequence of interactions between a user and a device. They are named after the comic-book-like sequences that are used to plan movie shots. - They are not interfaces, but they capture the time-based element of the interface in a static representation, which makes it easier to consider alternative designs side-by-side.

1.12. What is participatory design? (p.23)

- Is the design work that takes place as a collbaoration between developers and the people who will use the system.

2.7. What is "tacit" knowledge? How can you get it from someone? (p.44)

- Is the kind of knowledge that is difficult to transfer to another person by means of writing it down or verbalizing it. - One can get to the tacit knowledge if you dig and probe, and if you are persistent and patient.

1.11. What is cognitive science? How can user interface design benefit from cognitive science? (p.12)

- Is the study of thought, learning, and mental organization, which draws on aspects of psychology, linguistics, philosophy, and computer modeling. - UI design benefits from it b/c human-computer systems are often complex activites that require high level thought.

5.5. What is a direct manipulation interface?

- Is thought to make computers easy to use by introducing by making screen objects look and sort-of behave like things in the world (e.g. GUIs). (also: WIMP)

1.7. Why is it useful to have a "design rationale" at the end of a design process? (p.7)

- It is a written document that captures the decision-making process, and the tradeoffs, and documents why ideas are accepted or rejected. - (my words) Documenting the thought-process behind each design is essential to ensuring that it can be viewed later or tested against new ideas later on.

5.4. What is an affordance? What is the best way to figure out if something that you think is an affordance is really an affordance?

- It refers to perceivable characteristics of an object that helps a person to know (not"that makes it obvious" as the book defines) what the object can do, and how it can be manipulated. - Conduct a study in a real situation with real users

F.6. What are some specific design implications of Fitts' law?

- Large targets, small distances between targets are advantageous - Screen elements should occupy as much of available screen space as possible - The largest Fitts-based pixel is the one under the cursor - Screen elements should take advantage of screen edge - Streering tasks - moving linearly in a "tunnel" is more difficult than pointing.

5.10. Name and briefly describe the two basic types of user errors. Give a specific example of each.

- Mistakes are errors in choosing an objective or specifying a method of achieving it (going to the wrong menu for a certain setting). - Slips are errors in carrying out an intended method for reaching an objective (accidently exiting a window when you meant to minimize it).

5.10. Which type of error is more common for novices? More common for experts? Provide a general design guideline for minimizing each type of error.

- Mistakes more common for novices; slips more common for experts - To prevent mistakes: rep what is available or provide clear documentation - To prevent slips: have consistent low-level controls; minimize modes

5.7. What is a chunk? (p. 166; and slides)

- Organizing several interrelated bits of information into a single unit - Done by humans b/c we have limited capacity to hold information in mind

7.23 What should you do if you are participating in an experiment and the experimenter instructs you to perform a task as quickly and as accurately as possible? Draw the curve that explains your actions.

- Should tell them that it is impossible for one to be as quick and as accurate as possible. - Could be considered irresponsible to conduct such an experiment. - Viewing the speed-accuracy tradeoff graph, no where on the line is there a place where speed and accuracy are both at a maximum

1.5. How is the expression "there is no silver bullet" used in the context of computer science? (p.6)

- Software development is a very complex and wicked problem and there is "no silver bullet", no magical solution that will change that fact. (Fred Brooks, 1987) - There is no single innovation that will make software development costs drop in the same way that hardware costs will continue to drop.

5.6. What is an action sequence? (pp. 164-171) How does a user put together an action sequence? What is the relationship between planning an action sequence and HTA?

- Steps needed to achieve various system goals. - By chunking - They are both ways of organizing individual actions in a way that it can be best done by a user(?)

What specifies a task?

- Subtask/operation: is specified by a goal, the input conditions under which the goal is activated, the actions required to attain the goal, and the feedback indicating goal attainment.

H.3. HTA addresses what shortcoming in traditional time and motion studies?

- The classical methods of analysing tasks, such as Gilbreth's motion study which had been in use or half a century, were proving inadequate to describe tasks of increasing complexity and ever more important mental content. - R. B. Miller developed a method for manmachine task analysis that decomposed the main task functions into subtasks.

5.1. What is interaction design? Why is it difficult to represent interaction design? What are three different ways to represent an interaction design?

- The goal is to specify the mechanisms for accessing and manipulating task information; Tries to make sure that people can do the right things at the right time. - Interaction is difficult to represent because it is such a dynamic process. - Three ways to rep would be similar to types of prototypes - Interaction design relates to how easy it is for a user to: (a) translate his or her goals into the procedures for using a system to accomplish those goals (b) carry out those procedures (c) determine that he or she is making progress towards his or her goals.

1.2. How are scenarios used in user interface design? How do scenarios contribute to the design of easy-to-use, easy-to-learn, and useful human-computer interfaces?

- They are used in interface design to help researchers understand typical situations that the Human-Computer system will be used in. - ...

H.5. To what level of detail should you take an HTA?

- Until the source of performance failure, physical or cognitive, is identified and a solution can be hypothesised.

7.4 What are the ten guidelines of "heuristic evaluation"?

- Use simple and natural dialog - Speak the users' language - Minimize memory load - Be consistent - Provide feedback - Provide clearly marked exits - Provide shortcuts - Provide good error messages - Prevent errors - Include good help and documentation

5.8. What are keyboard shortcuts? How are they useful? How are they not so useful? (p.177)

- Useful because it decreases time/number of actions needed to perform an one (or more) interrelated activities - Not useful because each special command must be learned first (hard to remember all shortcuts)

6.5 what is a "Wizard of Oz" prototype?

- User is presented what looks/acts like real system, but human is triggering system backgrounds (does require strict set of rules) - Does require strict set of rules to ensure that human intelligence is a non-factor in the prototype (as that is impossible to code)

7.19 In the context of experimental design, what is validity? Internal validity? External validity?

- Validity: refers to best available approximation to the truth of propositions. - Internal validity: extent to which the experiment truly measures what it tries to measure; that is, within the context of this particular experiment - External validity: extent to which the experiment measures and hows something that is true about the world. (i.e. how applicable it is)

H.1. When and why was HTA first developed?

- Was first developed in the 1960s in order to overcome the limitations of classical time-and-motion methods in analysing complex nonrepetitive cognitively loaded tasks. - The process is to decompose tasks into subtasks to any desired level of detail.

6.6 Does a user interface (UI) prototype generally require computer programming? Explain.

- While certain high-fidelity prototypes for UI's may require some programming, they generally do not. Even if they do, they are for setting up front-ends and GUIs. - Many low-fidelity prototypes may not use computers at all, simply using pen and paper.

7.5 When conducting a "cognitive walkthrough", what four questions do you ask as you step through the interface?

- Will the user know the correct subgoal or subtask? - Will the user know that the correct action is available? - Will the user associate the correct action with the subgoal? - If the correct action is performed, will the user know progress is being made toward the goal?

1.10. What is GOMS? (p.12 and p.235-238)

- goals, operators, methods, and selection rules - Used to analyze the goals, methods, and actions of routine human-computer interaction

5.2. What are the seven stages of action? (Figure 5.1 on p. 160)

- task goal (choosing/form goal) - system goal (choosing/form intention) - action plan (planning) - execution - perception - interpretation - making sense

6.2 Name and describe three different types of user interface prototypes.

1. Storyboard: one or more pictures narrate a scenario; static representation of a dynamic system 2. Paper: paper-based prototypes can be very low-fidelity but very effective 3. Wizard of Oz: user is presented what looks/acts like real system, but human is triggering system backgrounds (does require strict set of rules) 4. Computer animation: 5. Scenario machine: 6. Rapid prototype: quick fabrication of physical or graphical prototype (used in manufacturing/dev) 7. Working partial system:

F.4. How are the parameters set?

?

7.9 A user observation study generally looks for a cause and effect relationship between A and B, to measure the extent to which A causes B. What are A and B?

A: independent variable B: dependent variable

2.6. What are stakeholders?

Are the many different groups of people who will be impacted by the development of the system.

What is a design scenario?

Describes a new vision for how a human need might be addressed. Note how it is abstract. It does not discuss any details of how any technology might work.

5.5. What are two advantages of direct manipulation over command-based interaction? Of command-based interaction over direct manipulation? Give an example of a task for which it would be best to provide a direct manipulation interface and a task for which it would be best to provide a command based interaction.

GUI advantages: - GUIs reduce the gulf of execution by making screen objects look and sort-of behave like things in the world. - It also makes it difficult for programmers to get away with assigning radically different functions to the same actions. Command-line advantages: - single place for all inputs - easy to develop tools for

7.14 Does task time matter for activities like online social networking or listening to music? Why or why not?

I believe that task time matters for any activity (albeit to different extents). Regardless of whether a system is important and used in high-stress situations or is used to space-out and scroll through different videos, task time does matter.(?)

7.20 Discuss threats to validity that should be considered when conducting a user observation study (a) in a lab and (b) in the real world.

In a lab: - external: how realistic is setting/social context In the real world - internal: how accurately can info be measured Often are tradeoffs between internal and external; conducting in lab may improve internal validity at the cost of decreased external validity (and vice-versa)

7.8 What is "storefront testing?" Give an example of a specific system that would be good to test in this manner, and a specific system that would not be good to test in this manner.

In which prototype placed in semi-public place (hallway in office). Passer-bys are encouraged to try the prototype and provide feedback. - "Walk up and use" systems would benefit (e.g. our time setting system), as storefront testing just generates instant feedback with users that may not closely represent real users. - High-pressure or high-expertise systems (e.g. new cockpit layout for a commercial aircraft) would not be good to test.

2.3. What is hierarchical task analysis (HTA)? (pp. 39-40 and Annett, 2003)

Is an approach to studying activities. Individual tasks (pieces of work) and subtasks are organized into a hierarchy, a tree-like structure. (p.39) HTA helps to transform a complex activity into increasingly easier-to-understand steps, so the entire task can be better understood.

2.1. What is requirements analysis?

Is the phase of software development in which the needs of clients with respect to a proposed project or technology are analyzed. (p.37)

What is usability engineering?

It is a somewhat formalized approach to planning, achieving, and verifying the usability of a system, in which usability refers to ease of use, ease of learning, and user satisfaction. The key idea is that measurable usability goals can be defined early in the process, and pursued and assessed during the process.

5.3. What is the "gulf of evaluation"?

It refers to the difficulty that people have in determining whether they are making progress towards those goals after executing an action.

H.4. What is the role of the "plan" in the HTA? Where does it appear in a diagram?

Relationship between a set of subtasks and the superordinate task. Appears near the superordinate task.

1.2. What is a scenario?

Simply a story about people carrying out an activity.

7.6 What are the two classic objective measures in human performance studies?

Speed and accuracy.

7.13 Why might you care about how quickly people can do a task using a user interface?

Speed is one of the most common measures taken when considering overall usability. Interfaces with better usability will often require less conscious thought (decision-making), fewer actions, etc., which all generally result in quicker use times.(?)

F.2. What does it predict? For what task?

This scientific law predicts that the time required to rapidly move to a target area as a function of the ratio between the distance to the target and the width of the target.

1.1. What is scenario-based usability engineering?

The basic idea is that descriptions of people using technology are essential in discussing and analyzing how the technology is (or could be) reshaping these human activities. (pp. 15-16)

K.2 Name and briefly describe (including approx. timings) the two activities that the eyes alternate between when a person studies a visual displays that has no moving objects.

The eyes are oriented with quick saccades - (25~50ms) Visual information is perceived during fixations - (200~400ms)

What is usability evaluation? (7)

Usability evaluation is a study to determine the ease of use and ease of learning of a system.

7.7 What is the "think aloud" protocol? When would you use it? When would you specifically not use it?

Where users narrate their goals, plans, reactions, and concerns as they work through the test tasks. - Can be analyzed to determine when person became confused or experienced usage difficulties - Should not be used when measuring task performance times and errors (as it are unnatural and will skew the data)