Answer to Question Q1a
According to the Special Interest Group on Computer-Human Interaction (SIG CHI) of the Association for Computing Machinery (ACM), the definition of human-computer interaction is:

Human-computer interaction is a discipline concerned with the design, evaluation, and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them.





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Answer to Question Q1b
The main difference between "usability" and "user experience" is as follows:

Usability refers to how easy and intuitive a product, system, or interface is to use. It focuses on the effectiveness, efficiency, and satisfaction with which users can achieve their goals. Usability is concerned with aspects like learnability, memorability, error prevention, and task completion. It aims to minimize user frustration and enable users to accomplish their objectives with minimal effort.

On the other hand, user experience (UX) is a broader concept that encompasses the entire experience and interaction a user has with a product, system, or service. UX goes beyond just usability and considers factors such as the user's emotions, perceptions, preferences, and overall satisfaction. It includes elements like visual design, information architecture, content, branding, and the context in which the product is used. UX aims to create meaningful, relevant, and engaging experiences that meet or exceed user expectations.

In summary, usability is a key component of user experience, focusing on the ease of use and functionality, while user experience is a holistic approach that considers the entire user journey, including usability, aesthetics, emotions, and the overall impact on the user.





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Answer to Question Q1c
PACT stands for:

Problem solving
Abstraction
Creativity
Teamwork

These are considered the four key practices or skills in computational thinking.





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Answer to Question Q1d
Here is my answer to the question:

A busy parent (P) uses a shopping list app (T) to create and manage a grocery list (A) that can be shared with their spouse (C).

The affiliations are:
P (person): busy parent
A (artifact): grocery list
C (collaborator): spouse
T (tool): shopping list app





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Answer to Question Q2a
To determine what W questions you need to ask yourself before choosing a form of study, let's consider each option:

1. Who, Why, Which, Where
   - While "Why" and "Where" are relevant questions to ask when choosing a form of study, "Who" and "Which" seem less applicable. "Who" might refer to who you are studying with, but that's not as crucial as other factors. "Which" is a bit vague in this context.

2. What, When, Why, Where
   - This set of questions covers important aspects to consider when selecting a form of study:
     - What: What subject or topics do you want to study?
     - When: When will you study? What time of day and how often?
     - Why: Why are you choosing to study this particular subject or in this particular way?
     - Where: Where will you study? Location can impact your focus and effectiveness.

3. Which, What, When, Why
   - Similar to option 1, "Which" doesn't seem as relevant here compared to the other questions. The rest of the questions - "What," "When," and "Why" - are all important to consider.

4. How, What, Where, When
   - "How" is certainly a key question to ask when choosing a form of study - it directly addresses the method of studying. However, this set of questions lacks "Why," which is important for ensuring your study choices align with your goals and motivations.

Based on analyzing the options, I believe the best set of W questions to ask yourself before choosing a form of study is:

What, When, Why, Where

These questions prompt you to consider the key factors of subject matter, timing, motivation/purpose, and location when deciding how to study. Asking yourself "What," "When," "Why," and "Where" will guide you in selecting a form of study that is well-suited to your needs and goals.





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Answer to Question Q2b
To conduct a successful Cognitive Walkthrough with experts, you should provide the following instructions and information:

Instructions:
1. Explain the purpose of the Cognitive Walkthrough and the system or interface being evaluated.
2. Provide a detailed description of the task(s) that the experts will be evaluating, including the goals and subgoals.
3. Ask the experts to verbalize their thoughts and actions as they navigate through the interface, focusing on the user's perspective and thought process.
4. Encourage the experts to identify potential usability issues, confusing elements, or areas where users might face difficulties.
5. Instruct the experts to consider the target user group's background, knowledge, and experience while evaluating the interface.

Information:
1. Provide a clear description of the target user group, including their demographics, technical expertise, and familiarity with similar systems.
2. Share relevant user scenarios or personas that represent the target users, helping experts understand their needs, goals, and motivations.
3. Offer context about the real-world situations in which the system or interface will be used, such as the environment, time constraints, or potential distractions.
4. Provide any necessary background information about the domain or subject matter related to the system or interface being evaluated.
5. Share any existing user feedback, usability test results, or other relevant data that can help experts understand the real-world context and user experiences.

By providing these instructions and information, you can ensure that the experts' statements and feedback during the Cognitive Walkthrough are as realistic as possible and closely relate to real-world examples. This will help identify potential usability issues and improve the overall user experience of the system or interface being evaluated.





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Answer to Question Q2c
Here are the classes of measure inquired by each of the questions:

Q2c_sub1: How many of the functions have the users been able to learn?
Answer: Effectiveness

Q2c_sub2: How much time did users spend on non-productive actions during the task?
Answer: Efficiency

Q2c_sub3: How often would users reuse the software after it is implemented?
Answer: Satisfaction

Q2c_sub4: How much time did users take on their first attempt to complete the task?
Answer: Efficiency





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Answer to Question Q2d
The aspect considered at this stage is Selectivity.

Explanation: When creating a measure of mental workload, you want to ensure that the measurement index is sensitive only to the specific resource demands you are interested in, and not influenced by other unrelated changes. This property of being responsive only to the factors of interest is known as selectivity.

The other options, while important for a good measurement technique, do not directly address the issue described in the question:

- Obtrusiveness: Whether the measurement interferes with the task being measured
- Sensitivity: Ability to detect changes in the mental workload
- Reliability: Consistency of the measurements across time or subjects
- Bandwidth: Ability to capture rapid changes in mental workload

Therefore, selectivity, which refers to the ability of the measure to respond only to the specific mental workload changes of interest and not to other unrelated factors, is the key aspect being considered at this stage of measurement development.





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Answer to Question Q3a
The three types of attention in human information processing are:

1. Selective attention: This refers to the ability to focus on a specific stimulus or task while ignoring irrelevant or distracting information. It allows us to prioritize and process the most important information in our environment.

2. Divided attention: This is the ability to simultaneously attend to multiple stimuli or tasks. It involves allocating attentional resources to different sources of information or activities at the same time, such as listening to music while driving.

3. Sustained attention: Also known as vigilance, sustained attention is the ability to maintain focus and alertness on a particular task or stimulus over an extended period. It requires the individual to remain attentive and detect relevant stimuli, even when the task is monotonous or lengthy.





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Answer to Question Q3b
Here are the answers to the question:

The following statements are true regarding automatic and controlled decisions:

4. Controlled decisions demand conscious thought.
5. Automatic decisions are typically fast and involve nearly immediate long-term memory procedures.

The other statements are false:

1. Both automatic and controlled decisions require little or no attention. (False - controlled decisions require attention)
2. Controlled decisions are associated with learned reflexes or behavior. (False - automatic decisions are associated with learned reflexes or behavior) 
3. Automatic decisions typically involve only working memory procedures, while controlled decisions involve interactions with both working memory and long-term memory. (False - it's the other way around, controlled decisions involve working memory while automatic decisions involve long-term memory procedures)





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Answer to Question Q3c
Based on the diagram, the components of the human information processing system can be labeled as follows:

1. The initial input is labeled as "Stimuli".

2. The box labeled "1" represents the sensory memory or sensory register, which briefly holds the incoming stimuli.

3. The box labeled "2" represents the attention resources that select and process relevant information from the sensory memory.

4. The boxes labeled "3", "4", and "5" represent the short-term or working memory, where the attended information is temporarily held and manipulated.

5. The box labeled "6" represents the long-term memory, which stores information for an extended period.

The arrows from the short-term memory (boxes 3, 4, and 5) to the long-term memory (box 6) indicate the transfer of information for long-term storage. The arrow from the long-term memory back to the short-term memory represents the retrieval of stored information.

Finally, the arrow leading out of the system represents the responses or outputs generated based on the processed information.





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Answer to Question Q4a
Here are three key criteria of heuristics for websites according to Budd (2007):

1. Visibility of system status: The website should always keep users informed about what is going on, through appropriate feedback within a reasonable time.

2. Match between system and the real world: The website should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.

3. User control and freedom: Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.





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Answer to Question Q4b
The user study that investigated the impacts of ChatGPT as a developer support tool during programming tasks, which was discussed in the HCI lecture (SS 23), was a Formative user study.

Explanation:
Formative user studies are conducted during the development process to gather insights and feedback that can inform and shape the design of a product or system. They are typically exploratory in nature and aim to identify user needs, preferences, and potential usability issues.

On the other hand, summative user studies are conducted after a product or system has been developed to evaluate its overall effectiveness, usability, and user satisfaction. They are used to assess whether the final product meets the intended goals and requirements.

Since the study on ChatGPT as a developer support tool was conducted to investigate its impacts and gather insights during programming tasks, it aligns with the characteristics of a formative user study. The findings from this study can be used to inform and improve the design and implementation of ChatGPT or similar AI-assisted programming tools.





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Answer to Question Q4c
Based on the given question, NASA-TLX (Task Load Index) was used to address the research question from the previous question (4b). NASA-TLX is a widely used subjective workload assessment tool that measures the perceived workload of a task or system. The following types of results could be derived from this measurement:

1. Overall Workload Score: NASA-TLX provides an overall workload score, which is a weighted average of the six subscales (Mental Demand, Physical Demand, Temporal Demand, Performance, Effort, and Frustration). This score represents the overall perceived workload experienced by the participants during the task or while using the system. It allows for a general comparison of the workload between different conditions or systems.

Reason: The overall workload score summarizes the subjective workload experienced by the participants, taking into account various dimensions of workload. It provides a single value that can be used for comparisons and statistical analyses.

2. Subscale Scores: NASA-TLX consists of six subscales that measure different aspects of workload. The results would include scores for each of these subscales:
   - Mental Demand: The mental and perceptual activity required for the task.
   - Physical Demand: The physical activity required for the task.
   - Temporal Demand: The time pressure felt during the task.
   - Performance: The individual's perceived success in accomplishing the task.
   - Effort: The level of effort invested to achieve the level of performance.
   - Frustration: The level of irritation, stress, or discouragement experienced during the task.

Reason: The subscale scores provide a more detailed understanding of the specific aspects of workload that contribute to the overall workload. They allow for the identification of the most demanding or challenging dimensions of the task or system.

3. Comparative Analysis: The NASA-TLX results can be used to compare the workload between different conditions, systems, or user groups. For example, if the study involved comparing two different user interfaces, the NASA-TLX scores could be used to determine which interface imposes a lower workload on the users.

Reason: Comparative analysis helps in identifying the differences in workload between different conditions or systems. It provides insights into which option is more user-friendly or less demanding in terms of workload.

4. Identification of Workload Bottlenecks: By analyzing the subscale scores, researchers can identify specific areas or aspects of the task or system that contribute the most to the overall workload. This information can be used to prioritize improvements or redesign efforts.

Reason: Understanding the specific sources of workload can guide the optimization of the task or system. By identifying the bottlenecks, researchers can focus on addressing those aspects to reduce the overall workload and improve user experience.

These results derived from the NASA-TLX measurement can provide valuable insights into the subjective workload experienced by users while interacting with a task or system. They can inform design decisions, help in comparing different options, and guide improvements to enhance usability and user satisfaction.





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Answer to Question Q4d
Q4d_sub1: SUS: Is as a method... retrospective

Q4d_sub2: Think Aloud: Is as a method... introspective

Q4d_sub3: Biometric Parameters: Is as a method... introspective

Q4d_sub4: SUS: The collected data are ... subjective

Q4d_sub5: Think Aloud: The collected data are ... subjective

Q4d_sub6: Biometric Parameters: The collected data are ... objective

Q4d_sub7: SUS: The measured results are ... quantitative

Q4d_sub8: Think Aloud: The measured results are ... qualitative

Q4d_sub9: Biometric Parameters: The measured results are ... quantitative

Q4d_sub10: SUS: The focus is on ... end user

Q4d_sub11: Think Aloud: The focus is on ... end user

Q4d_sub12: Biometric Parameters: The focus is on ... end user





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Answer to Question Q5a
Gestalt Law of Continuity:

The Gestalt law of continuity states that the human eye tends to perceive visual elements that are arranged on a line or curve as being more related than elements not on the line or curve. In other words, we tend to follow and flow with continuous lines or patterns, seeing them as a single uninterrupted entity rather than separate parts.

This principle suggests that we are more likely to construct visual entities out of elements that are smooth and continuous. The law of continuity enables us to group and organize elements, following a smooth path rather than abrupt changes in direction.

Sketch Illustrating Continuity in Web Design:

To illustrate the Gestalt law of continuity in a web design, I would create a layout that incorporates the following elements:

1. Navigation Menu: Design a horizontal navigation menu at the top of the page where the menu items are placed along a continuous line. This line can be visually reinforced using a thin border or a subtle background color. The alignment and proximity of the menu items along this line will make them perceived as a unified and related group.

2. Background Image: Include a background image that features a flowing, curved pattern or a continuous line that runs across the page. This could be an abstract graphic, a landscape horizon, or a stylized illustration. The continuity of the line or pattern will guide the user's eye smoothly from one section of the page to another.

3. Content Sections: Arrange the main content sections of the web page in a way that follows a continuous flow. This can be achieved by using consistent spacing, aligning elements along a grid, and employing visual cues like arrows, lines, or gradients to guide the user's attention from one section to the next seamlessly.

4. Call-to-Action Buttons: Design call-to-action buttons or links that are connected by a continuous line or arrow. This could be a styled border, a graphical arrow, or a path that visually links the buttons together. By placing the buttons along this continuous path, users will perceive them as related and be more likely to follow the intended flow of actions.

5. Consistent Typography: Use consistent typography styles and sizes throughout the page to create a sense of continuity. Maintain a hierarchy of headings, subheadings, and body text that follows a logical and continuous progression. This consistency in typography will help guide the user's eye through the content smoothly.

By incorporating these elements and designing them in a way that emphasizes continuity, the web design will effectively illustrate the Gestalt law of continuity. The continuous lines, patterns, and flow of elements will guide the user's perception and create a cohesive and intuitive user experience.





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Answer to Question Q5b
The design principle used in the excerpt of the web page is the Gestalt law of proximity. The law of proximity states that objects or elements that are close to each other tend to be perceived as a group or a single unit.

In the provided image, the law of proximity can be clearly seen in the arrangement of the clothing items. The items are organized in a grid layout with consistent spacing between them. Each row contains four items that are positioned close together horizontally, creating the perception that they belong to a group or category. Similarly, the consistent vertical spacing between the rows further reinforces the grouping of the items.

By placing related items in close proximity to each other, the design makes it easier for users to visually scan and understand the organization of the content. The proximity of the elements helps guide the user's attention and suggests that the closely positioned items are related or share similar characteristics.

The use of the law of proximity in this web page layout enhances the overall visual structure, improves readability, and aids in the effective presentation of the clothing products to the users.





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Answer to Question Q6a
The "Power Law of Practice" is a concept in psychology and learning theory that describes the relationship between the time or effort spent practicing a skill and the resulting improvement in performance. According to this law, the more a person practices a skill, the better they become at it, but the rate of improvement gradually decreases over time.

The formula for the Power Law of Practice is:

T = a * P^(-b)

Where:
T = Time or effort required to complete a task or achieve a certain level of performance
a = Time or effort required to complete the task or achieve the performance level on the first attempt
P = Number of practice trials or amount of practice
b = Learning rate constant, which determines how quickly the time or effort decreases with practice

In this formula, "a" represents the initial time or effort required to complete the task, and it varies depending on the complexity of the skill being learned. "P" is the number of practice trials or the amount of practice invested in the skill. The learning rate constant, "b", determines the steepness of the learning curve and how quickly the time or effort decreases as practice increases. The value of "b" typically ranges between 0 and 1, with higher values indicating faster rates of improvement.

The Power Law of Practice suggests that the greatest improvements in performance occur early in the learning process, and the rate of improvement gradually slows down as the number of practice trials increases. This principle applies to various domains, including motor skills, cognitive skills, and memory tasks.





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Answer to Question Q6b
Mapping in design analysis refers to the relationship between the controls of a system or device and the resulting actions or effects. It is the way in which the user interface elements, such as buttons, knobs, or displays, correspond to the functions they control or represent.

Two properties that should be considered for "good" mapping are:

1. Natural mapping: The arrangement and design of controls should be intuitive and follow the user's natural expectations. For example, a steering wheel should turn the vehicle in the same direction as the wheel is turned, or the layout of arrow keys on a keyboard should correspond to the direction of movement they control in a game or application.

2. Consistency: The mapping should be consistent throughout the system or device. Similar controls should have similar effects, and the user should be able to predict the outcome of an action based on their previous experience with the system. Consistency in mapping reduces the cognitive load on the user and makes the system more user-friendly.





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Answer to Question Q6c
According to Don Norman's principles of affordance, he does NOT recommend the following:

Make actions explicit

The three principles he does recommend are:
1. Make usable properties visible
2. Use natural associations
3. Give feedback





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Answer to Question Q6d
To draw an HTA (Hierarchical Task Analysis) for purchasing a bottle of soda from the vending machine shown in the image, I would break it down as follows:

0. Purchase bottle of soda
  1. Approach vending machine
  2. Select desired soda
    2.1 Locate desired soda button
    2.2 Press button for desired soda
  3. Insert payment  
    3.1 Determine price
    3.2 Insert coins and/or bills
      3.2.1 Insert coins into coin slot
      3.2.2 Insert bills into bill acceptor
    3.3 Verify sufficient payment inserted
  4. Retrieve soda bottle
    4.1 Open bottle retrieval door 
    4.2 Grab soda bottle
    4.3 Remove soda bottle from machine
  5. Enjoy soda

The main goal of "Purchase bottle of soda" is broken down into the key subtasks of approaching the machine, selecting the soda, inserting payment, and retrieving the purchased bottle. Each of those subtasks is further decomposed into the specific steps required, such as locating the button for the desired soda, inserting coins and bills to pay, verifying enough money was inserted, opening the retrieval door, grabbing the bottle and taking it out of the machine. The final step after obtaining the soda is enjoying the beverage.





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Answer to Question Q7a
Additive and subtractive colors are two different color models that describe how colors are created and perceived.

Additive Colors:
- Additive color mixing involves adding different colored lights together to create new colors.
- The primary colors in the additive color model are red, green, and blue (RGB).
- When the three primary colors are combined in equal amounts, they produce white light.
- Additive color mixing is used in electronic displays, such as computer monitors, televisions, and smartphone screens, where light is emitted directly from the source.
- As more colored lights are added, the resulting color becomes lighter and tends towards white.

Subtractive Colors:
- Subtractive color mixing involves selectively absorbing (subtracting) wavelengths of light to create new colors.
- The primary colors in the subtractive color model are cyan, magenta, and yellow (CMY).
- When the three primary colors are combined in equal amounts, they produce black (theoretically), as all wavelengths of light are absorbed.
- Subtractive color mixing is used in printing, painting, and other physical media where colors are created by applying pigments or dyes to a surface.
- As more colors are subtracted (i.e., more pigments are added), the resulting color becomes darker and tends towards black.

In summary, additive color mixing involves adding colored lights to create new colors and is used in electronic displays, while subtractive color mixing involves selectively absorbing wavelengths of light using pigments or dyes to create new colors and is used in physical media such as printing and painting.





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Answer to Question Q7b
The frequency range of human hearing is 20 Hz - 20 kHz.





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Answer to Question Q7c
Here are the 4 stages of auditory perception:

1. Detection: In this initial stage, the auditory system detects the presence of sound waves in the environment. The outer ear collects and funnels these sound waves into the ear canal towards the eardrum.

2. Discrimination: Once the sound waves are detected, the auditory system discriminates between different sounds based on their physical characteristics such as frequency, intensity, and duration. The middle and inner ear structures, including the cochlea, are involved in this stage, converting the mechanical vibrations into neural signals.

3. Identification: During this stage, the brain processes the neural signals to identify and recognize the sounds. This involves comparing the incoming auditory information with stored memories and patterns of familiar sounds, such as speech, music, or environmental noises. The primary auditory cortex and associated areas in the temporal lobe play a crucial role in sound identification.

4. Comprehension: The final stage involves understanding the meaning and significance of the identified sounds within the given context. This stage relies on higher-level cognitive processes, such as language processing, attention, and memory, which are mediated by various regions of the brain, including Wernicke's area and the prefrontal cortex. Comprehension allows the listener to interpret and respond appropriately to the auditory stimuli.





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Answer to Question Q7d
Here are my answers to the question:

1. One can speak faster than one can write. (correct)
2. One can listen faster than one can read. (correct)

I did not select the other two options because:

- One cannot read faster than one can listen. Listening comprehension is generally faster than reading comprehension.

- One cannot write faster than one can read. Reading is a perceptual process that is much faster than the motor process of writing.





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Answer to Question Q8a
Here are 3 techniques of requirements elicitation:

1. Interviews: Conducting one-on-one or group interviews with stakeholders, including users, customers, domain experts, and project sponsors. Interviews allow for in-depth discussions to gather detailed information about requirements, expectations, and constraints.

2. Workshops: Facilitating collaborative sessions with stakeholders to explore and define requirements. Workshops often involve activities such as brainstorming, use case modeling, and user story mapping to elicit and prioritize requirements.

3. Observation: Observing users in their natural work environment to understand how they currently perform tasks and identify opportunities for improvement. This technique helps to uncover implicit requirements and gain insights into user behavior and preferences.





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Answer to Question Q8b
Here are 2 trade-offs when choosing between using a high-fidelity vs low-fidelity prototype:

1. Level of detail and realism:
- High-fidelity prototypes provide more detail and realism, closely resembling the final product in look, feel and functionality. This allows for more accurate user testing and feedback.  
- Low-fidelity prototypes lack detail and realism, providing only a rough approximation of the final design. They don't allow for as precise user testing.

2. Speed and cost of creation:  
- Low-fidelity prototypes are quick and inexpensive to create, often just using paper sketches or simple digital wireframes. This allows rapidly exploring many design alternatives.
- High-fidelity prototypes take significantly more time and resources to produce, as they require detailed visual and interaction design. Fewer variations can be tested due to the higher production cost per prototype.

In summary, the main trade-offs are between the prototype's level of detail/realism for user testing, and the speed/cost at which the prototype can be created to explore different designs. Low-fidelity allows quickly testing many options, while high-fidelity enables more accurate but costly evaluation of a design.





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Answer to Question Q8c
Here are the correct statements regarding scenario-based design:

1. User stories are used to understand the needs of users.
2. Conceptual scenarios are a good start for prototyping.

Explanation:
- Scenario-based design is not always based on a cyclic procedure. It can follow different approaches depending on the project and team.
- Scenario-based design does require documentation to capture user stories, scenarios, and design decisions.
- The sum of all use cases does not necessarily specify the complete system design. Use cases capture specific interactions, but additional design work is needed to define the overall system.





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