Hierarchical Task Analysis PDF

HIERARCHICAL TASK ANALYSIS Group 3 WHAT IS HTA? Hierarchical task analysis (HTA) is an Hierarchical Task analysis(HTA) is a underused approach in user experience, method for analyzing tasks using a but one you can easily apply when either hierarchical structure. You start over...

HIERARCHICAL TASK ANALYSIS Group 3 WHAT IS HTA? Hierarchical task analysis (HTA) is an Hierarchical Task analysis(HTA) is a underused approach in user experience, method for analyzing tasks using a but one you can easily apply when either hierarchical structure. You start overall, modifying an existing design or creating a break this down into top level sub-goals new design. into more detail to create a tree-like structure. Hierarchical Task Analysis is a fundamental technique for understanding tasks and processes in Human Factors. HIERARCHICAL TASK ANALYSIS 2 WHAT IS HTA? Describes an activity in terms of The goal of HTA is to produce a specific goals, subgoals, task hierarchy pf steps that must operations and plans. completed some high-level tasks. HIERARCHICAL TASK ANALYSIS 3 APPLYING HIERARCHICAL TASK ANALYSIS TO USER EXPERIENCE Hierarchical task analysis requires a detailed understanding of users’ tasks. You can achieve this understanding by: Identifying the users’ primary goals Detailing the steps users must perform to accomplish their goals Optimizing these procedures HIERARCHICAL TASK ANALYSIS 4 In the example HTA, the task is broken down into subtasks, expressing the relationships between the parent task and its subtasks through a numbering scheme. This hierarchical task analysis is very coarse from a user experience standpoint. It does not communicate anything about what is happening at the level of a user’s interaction with the system. However, it does give a clear understanding of the task’s high-level steps. HIERARCHICAL TASK ANALYSIS 5 A more complete task analysis would ultimately get down to the level of user interactions. To illustrate, Subtask 1.4, “Complete address,” would break down as follows: HIERARCHICAL TASK ANALYSIS 6 Optionally, you can provide an illustration of the screen on which a user performs this task, helping to put this interaction in context. Figure 2 shows the screen for the “Complete address” task. HIERARCHICAL TASK ANALYSIS 7 It is advisable to create a plan that describes the way in which a hierarchical task analysis assembles the subtasks that let users achieve a particular goal and any conditions the subtasks must fulfill. Users can simply work through the subtasks in a hierarchical task analysis, so keeping the plan separate from the tasks provides an additional degree of flexibility. For the example hierarchical task analysis, there could be two different plans, as follows: 1. If a user is new to the system, complete Task 1. 2. If a user has registered and is signed in, complete Tasks 1.1, 1.2, and 1.5. HIERARCHICAL TASK ANALYSIS 8 HTA EXAMPLE: HIERARCHICAL TASK ANALYSIS 9 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS It lets you objectively There may be several It enables effective It support user compare different competing approaches approaches to the users experience experience design to the same problem, design , because reuse. User supporting same task—in so ensuring your team terms of the numbers and designers can experience design types of steps the uses common language and a consistent understand how a patterns are a useful approaches require. The hierarchical task analysis approach to system works, at step toward user provide a framework in hierarchical task whatever level of experience design which you can capture such analysis can help you abstraction is most reuse, but they a design rationale and refer compare them fairly. appropriate. describe only the to any related documentation. high-level Principles of Interactions. HIERARCHICAL TASK ANALYSIS 10 STEPS IN CONSTRUCTING HIERARCHICAL TASK ANALYSIS Step 1: Step 2: Step 3: Step 4: Step 5: Setting Identifying Calculate Ceasing Re- Generating Goals Constraints Criticality Description Hypotheses / Design Fix Step 9: Step 6: Step 8: Step 7: Cost- Step 10: Challenge Re- Record the Benefit Clean Up the Description Analysis Analysis Constraints HIERARCHICAL TASK ANALYSIS 11 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 1: SETTING GOALS -Start with the main work goal assoiciated with the problem. This will depend on the purpose of task analysis. You might use your focus statement ( from the focus project ). For example your goal is to order online. HIERARCHICAL TASK ANALYSIS 12 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 2: IDENTIFY CONSTRAINT - Next , identify constraints associated with attaintment of goal or problem solution. Constraint are important because they affect the design options that might be adopted to achieve goals. Example: You want to buy the laptop you need , but when you look at the price of the product, your money is still not enough. HIERARCHICAL TASK ANALYSIS 13 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 3: CALCULATE CRITICALITY -Now that you have a step of your HTA , you need to decide if it should have lower level boxes below it , which requires you to determine the “criticality” of the task element. Example: You might decide that “ordering online” is highly critical, because sometimes ordering online can be a scam. HIERARCHICAL TASK ANALYSIS 14 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 4: CEASING RE-DESCRIPTON -If the goal is not critical , dont decompose it further. If you have more goals , go back to step 1 , if no go to step 10. HIERARCHICAL TASK ANALYSIS 15 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 5: GENERATING HYPOTHESIS/DESIGN FIX -If the current performance of the goal is unacceptable (high criticaly), then attempt to determine the cause or a solution to the problem (depending on the goals of your project). Example: Because ordering online can be a scam you need to check if the seller is legit or just buy it personally. HIERARCHICAL TASK ANALYSIS 16 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 6: COST-BENEFIT ANALYSIS - Now that you are looking into design hypothesis, you need to determine whether the benefit outweighs the cost. You might not able to decide this until after doing more analysis. Example: In step 5 you include “buying it personally” was a good solution but because you have still classes to attend on week days and works on weekends you don’t have enough time to go to city. HIERARCHICAL TASK ANALYSIS 17 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 7: RECORD THE ANALYSIS -Your design hypotheses (including the one you’ve rejected) are’nt captured in the HTA , so record your design hypotheses and justification as well. If you have more sub-goals to analyze , go back to Step 1 , if not , go to HIERARCHICAL TASK ANALYSIS 18 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 8: RE-DESCRIPTION -The re-description will include a set of subordinate operations or sub-goals and a “plan” specifying the conditions when each operation s appropriate HIERARCHICAL TASK ANALYSIS 19 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 9: CHALLENGE THE CONSTRAINT -If management ruled out a design solution based on cost , you might then revise this cost constraint if there are no suitable alternative design hypotheses. Example: If you decide to buy it personally you just need to make time on you schedule to buy the laptop you need. If you succeed in challenging the constraints go back to step 7 , if not go back to step 1 , focusing on the next sub-goal. HIERARCHICAL TASK ANALYSIS 20 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS Step 10: CLEAN UP -PATRICK , GREGOV, & HALLIDAY (2000) provide a few rules for the HTA should obey 1. HIERARCHICAL REPRESENTATION – the completed HTA represented as a hierarchy of operations and sub- operations. 2. LOGICAL DECOMPOSITION RULE – each level of an HTA should be logical decomposition of its higher level as opposed to temporal order , a kinds-of hierarchy, prequisites etc. HIERARCHICAL TASK ANALYSIS 21 THE BENEFITS OF HIERARCHICAL TASK ANALYSIS 3. LOGICAL EQUIVALENCE – HTA requires that an operation be analyzed into a set of sub-operations , which when combined with a plan are logically equivalent to the operation. 4. SPECIFICATION OF PLANS – when an operation is re-described into a set of subordinate operations, these are organized by a plan that specifies the condtions under which operations are performed. Therefore, plans should be specified at each level of re-description in the analysis. 5. P x C RULE – this criterion concerns the extends to which the P x C stopping rule has been applied correctly to determine the lowest. HIERARCHICAL TASK ANALYSIS 22