Conceptual Extension to GOMS Models for Complex Scenarios
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Introduction to GOMS
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Today we are discussing the GOMS models, which are essential for understanding user interaction beyond simple tasks. Can anyone tell me what GOMS stands for?
Goals, Operators, Methods, and Selection Rules!
Exactly! GOMS provides a structured way to analyze how users interact with systems. Why do you think having structured representations is important?
It helps in identifying the steps users take to complete tasks, right?
Correct! It brings clarity to the complex interactions by breaking them down into manageable components.
So, how does GOMS differ from simpler models like KLM?
A great question! Unlike KLM, which focuses on task execution time for expert users, GOMS provides a framework for tasks with multiple methods and decision-making contexts.
To help remember, think of GOMS as a guide to 'Gaining Objective Methods systematically.'
Complex Tasks and GOMS
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Let's dive deeper into why GOMS is essential for complex tasks. Can someone explain what happens when a task has multiple methods?
I think it means users can approach the goal in different ways, depending on the context.
Exactly! For instance, when saving a file, a user might use 'Save' or 'Save As.' GOMS helps illustrate these options.
How does GOMS handle the decision-making part?
Great question! GOMS includes selection rules guiding users in context, helping them choose the most efficient method for achieving their goal.
A useful tip is to think of GOMS as helping 'Guide Options for Method Selection.'
Practical Application of GOMS
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Now, letβs discuss modeling tasks with GOMS. If we were to model a complex task, what would be our first step?
We'd define the top-level goal, right?
Absolutely! Then weβd break down that goal into sub-goals. Can anyone provide an example of a top-level goal?
Processing a customer order could be a top-level goal.
Perfect! Next, what would be sub-goals for that?
Entering customer information and completing payment are sub-goals.
Great work! Finally, we need to specify the methods for achieving each sub-goalβensuring we outline various ways users can approach these tasks.
And remember, for modeling, think of 'Gaining Optimal Methods step-by-step.'
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section discusses the need for GOMS models in complex tasks that involve multiple methods and decision-making. It emphasizes how traditional models like KLM are limited to expert users performing routine tasks, and GOMS provides a framework for representing task hierarchy and user knowledge in more detail.
Detailed
The GOMS (Goals, Operators, Methods, Selection Rules) model offers vital insights into how users achieve complex tasks through structured and hierarchical representations. This section explains the necessity of extending KLM to GOMS models, particularly when tasks involve multiple methods for achieving a goal, decision points influenced by context, and knowledge articulation for effective interaction. The ability to represent task complexity through GOMS enables designers to better accommodate real-world scenarios where users might encounter varied ways to achieve their objectives while highlighting the cognitive steps and decision-making processes involved.
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Beyond Simple Execution Time
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Chapter Content
While KLM is excellent for the "how long" of a simple, error-free task, real-world tasks are often more complex, involving decision points, alternative strategies, and problem-solving.
Detailed Explanation
In this chunk, we learn that the Keystroke-Level Model (KLM) is useful for estimating the time it takes to complete straightforward tasks without errors. However, real-world tasks are not always as simple. Often, tasks require users to make decisions, choose among various strategies, and solve unexpected problems. Because of this complexity, KLM alone may not provide a complete picture of user performance, especially when tasks involve multiple steps or decision-making processes.
Examples & Analogies
Imagine you're trying to bake a cake. If you have a straightforward recipe that lists the steps in order without any alternative actions, KLM can help you estimate how long each step takes. However, real baking often requires you to make choices (like what flavor to use), resolve issues (like if your cake is too wet), and decide which tools to use (like a hand mixer versus a whisk). Just like in baking, tasks in software may not always follow a straight line but can branch out in many directions based on user preferences or situations.
When GOMS Becomes Essential
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Chapter Content
For tasks that involve multiple methods for a goal, if the user has several distinct ways to achieve a sub-goal, and their choice depends on context (e.g., "save as" vs. "save"), GOMS's "Methods" and "Selection Rules" become indispensable.
Detailed Explanation
This chunk discusses the situations where using the GOMS model becomes crucial. It highlights that when users have various methods to reach a specific goal, understanding their choices is vital. GOMS helps model these methods and the selection rules, which dictate which method a user may choose based on the situation. For example, a user may have different ways to save a document: they could use the 'Save' option or 'Save As' depending on their intent. GOMS captures this user's decision-making process and ensures that the design accommodates these different pathways.
Examples & Analogies
Think of it like traveling to a destination. There are often several routes you can take. If the road is congested, you might choose a less busy route, or if you're in a hurry and familiar with shortcuts, you might take those instead. Similarly, users in a software environment will choose different methods based on the context they're in. GOMS identifies and organizes these routes, helping designers understand how users navigate their options.
Hierarchical Task Structure
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Chapter Content
If a task naturally decomposes into nested sub-goals, a full GOMS model explicitly represents this cognitive hierarchy, offering a clearer picture of the user's mental model.
Detailed Explanation
In this chunk, we discover that many tasks consist of several layers of goals, with sub-goals contributing to the larger task. GOMS allows for the representation of these different levels in a structured manner. For instance, a task like creating a new project in a software application may include sub-goals like setting project parameters, naming the project, and defining user roles. By using GOMS to model these nested goals, designers can better understand how users think about and complete their tasks, leading to more intuitive software design.
Examples & Analogies
Imagine building a house. You can't just put up walls; first, you need foundational work like laying the groundwork, deciding on a blueprint, and acquiring permits. These are like sub-goals leading to the larger goal of building the house. Just as a structured approach helps you build a house successfully, using GOMS helps software designers understand the complex layers of user tasks, ensuring that all necessary components are addressed.
Understanding User Knowledge
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Chapter Content
GOMS forces a designer to articulate the precise knowledge an expert user must possess to use the system effectively, which can inform training and documentation needs.
Detailed Explanation
This section emphasizes the importance of understanding what knowledge a user needs when interacting with a system. GOMS facilitates this understanding by breaking down goals and the methods to achieve them. It helps in identifying what information or skills users need to navigate the software confidently, thereby guiding designers in creating better training materials and documentation aimed at bridging any gaps in user knowledge.
Examples & Analogies
Consider learning to ride a bike. You donβt just get on the bike and start pedaling - you need to know how to balance, steer, and brake. Similarly, understanding what knowledge users require to complete tasks in a software application is essential to ensure they can use it easily. GOMS helps clarify these needs, aiding in developing user manuals that truly address user requirements and enhance their experience.
Initial Steps for a GOMS Case Study
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Chapter Content
- Define Top-Level Goal: Start with the main objective (e.g., GOAL: PROCESS-CUSTOMER-ORDER). 2. Identify Sub-Goals: Break the main goal into logical sub-goals (e.g., GOAL: ENTER-CUSTOMER-INFO, GOAL: ADD-ITEMS-TO-CART, GOAL: COMPLETE-PAYMENT). 3. Specify Methods for Each Goal/Sub-Goal: For each goal or sub-goal, list all the distinct sequences of operators and lower-level sub-goals that an expert user might employ to achieve it. 4. Define Selection Rules: For any goal with multiple methods, articulate the precise rules an expert would use to choose one method over another (e.g., "IF customer is new THEN USE Method: New-Customer-Entry ELSE USE Method: Existing-Customer-Lookup"). 5. Decompose to Operators: Eventually, break down all methods into their lowest-level KLM-like operators. 6. Calculate Path Times: Sum the operator times for each distinct path through the GOMS hierarchy to get predicted execution times for various scenarios.
Detailed Explanation
This final chunk outlines how to conduct a GOMS case study effectively. It encourages designers to follow a structured approach, starting with defining a primary goal and breaking it down into smaller, more manageable sub-goals. Designers should then specify various methods for achieving these goals, determine the selection rules for when to apply each method, and finally analyze the operators involved in each method. This process will facilitate predicting how long tasks will take, thus optimizing user interaction.
Examples & Analogies
Think of organizing a community event. You first define the top-level goal, like 'Host a Charity Fundraiser.' Then you identify sub-goals like 'Book a venue,' 'Hire catering services,' and 'Promote the event.' Each of these can have multiple methods for completion, much like how you might book a venue online or over the phone depending on circumstances. By breaking down the process, GOMS helps provide clarity and makes sure all steps are accounted for, ensuring the event is successful.
Key Concepts
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Hierarchical Structure: GOMS models break down tasks into goals, methods, and selection rules to manage complexity.
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Decision Making: GOMS incorporates user decision-making into task analysis.
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Multiple Methods: GOMS allows for the exploration of several methods to achieve a task goal.
Examples & Applications
In a word processing application, a user can save documents using both keyboard shortcuts and menu options.
When entering online banking information, users may select various methods: typing directly, using drop-down menus, or saving auto-filled fields.
Memory Aids
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Rhymes
To save a task with plenty of flair, decide your goals and take great care, methods and rules will lead you right, choosing with GOMS will bring delight.
Stories
Imagine a chef in a kitchen as a model of user tasks. The chef must identify ingredients (goals), decide how to prepare them (methods), and based on the time available (selection rules), choose the best dish to create. This reflects how GOMS helps users navigate tasks.
Memory Tools
Use 'GOMS' as a reminder of 'Goals, Operations, Methods, Selection Rules' when analyzing tasks.
Acronyms
G.O.M.S. can stand for 'Getting Objectives Managed Systematically' to help remember the focus of the model.
Flash Cards
Glossary
- GOMS
A family of predictive models (Goals, Operators, Methods, Selection Rules) that describe user interaction with systems.
- Goals
High-level objectives or intentions that drive user interaction within a task.
- Operators
The basic actions performed by users to move towards achieving their goals.
- Methods
Pre-defined sequences of actions used by users to achieve specific goals.
- Selection Rules
Rules that help the user decide which method to adopt based on context or personal preference.
Reference links
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