The 7 Steps of Hierarchical Task Analysis: Part 2

In this post we are going to focus on the first step in Hierarchical Task Analysis: deciding what to analyze and how to analyze it.  Most beginners rush through this step to start creating a task hierarchy, but with experience, you are able to appreciate the importance of thinking through the purpose of your analysis and what you are trying to achieve.  If you get this first step wrong, the entire analysis is at risk.

STEP 1: DECIDE WHAT TO ANALYZE AND HOW TO ANALYZE IT 

This is where you determine the boundaries or scope of your analysis. Factors to consider include: 

  • The context of the analysis. The analysis of your product could be focused on the main operation, ie. turning it on, using it, and turning it off again. However, there may be broader value to your stakeholder in looking at how the product is acquired, installed, and upgraded. It depends on what the real need for the analysis is. Exploring this upfront with your stakeholder(s) - the people who will make use of the results of the analysis - will improve the value of the analysis and keep the work on-target.
  • The level of task required. Task analysis can be taken to very fine levels of detail from a high level view across a group that provides a function to a company down to the keystrokes required on a particular interface (and the cognitive processes behind selecting those keystrokes). It is tempting for people carrying out their first analysis to spend a lot of time focused on capturing the detail of a task without looking up occasionally to reflect on what is really required in order to actually accomplish the task in question. Is a comprehensive analysis required in order to identify all safety critical tasks, or is an analysis of the high level tasks required in order to broadly define the capabilities of a system?
  • Task properties that need to be recorded. Often design problems can be solved by simply recording the steps required to analyze a goal, however, it is sometimes useful to record more information about the tasks in order to tease out critical aspects of the activities. These pieces of information are called task properties.  Any analysis must take into account the range of factors which influence the human performance in a complex system. These can include recording interfaces, training requirements, team organization, communications, workload. time pressure, environmental factors, among many others.  The main objective of any task analysis method is to enable the analyst to obtain data on the issues of concern and assess whether design proposals are justified in terms of expectations in regard to human activity.

The analysis process can provide systematic evidence for demonstration of conformance, or it may identify mismatches between required and expected performance levels. Where there are mismatches, the analytic process can be used to propose and test remedial measures.  For instance, in order to decide where additional training about safety could most effectively be applied, the analysis may find it useful to record an actual or projected rating for the likelihood of a user making a safety critical error on each task. A report listing those tasks where a critical error is most likely to occur will guide the design of the training program. As you become a more experienced analyst, you will more easily choose a style of approach that you know will be most appropriate for your approach to a problem.

EXAMPLE: HIERARCHICAL TASK ANALYSIS IN SUPPORT OF A NEW WEBSITE DESIGN 

Let's assume your company makes cars, and you are assigned to a team that is designing a web site to help users with any questions they may have about their cars.  This example will use Hierarchical Task Analysis to explore this problem.

  • Context of the analysis. The first question to address is what outcome your company hopes to achieve by the creation of this website.  For instance, does your company hopes to reduce costs by replacing the printed user manual with a web based information system?  Your analysis will need to be a very comprehensive attempt to include all the information that customers might look for in their user manual.  There may also need to be analysis of key information that customers need in a roadside emergency when web access might not be available.  Let's assume for our example that your company wants to reduce the demand placed on customer support operators by customers calling for specific instructions.  It is hoped that the new website would make it easier for customers to answer their own questions.

GOAL: REDUCE DEMAND PLACED UPON CUSTOMER SUPPORT BY PROVIDING A WEB BASED RESOURCE TO ANSWER FREQUENTLY ASKED QUESTIONS

  • Level of detail required. Since the intent of the analysis is to answer customer questions, the level of detail of the analysis must be sufficient to satisfy the customer answering the question.  An important part of this answer lies in understanding the customer's needs and familiarity with the car.  One approach might be to assume that the customer knows very little, this would require a thorough level of detail in the analysis of each answer.  Of course, the downside to this approach is that many of your customers may need information but may be turned off by overly detailed instructions.  The key insight here is that the level of detail required is different for different customers.

STOPPING RULE: STOP BREAKING DOWN TASKS WHEN THE TASK CAN BE COMPLETED BY THE MOST UNFAMILIAR OF CUSTOMERS

  • Task properties to record. Given our earlier discussion, it seems that there are three categories of information that may be needed be recorded.  First, it would be useful to record information that any customer might find useful about any step.  This might include: expected time to complete, tools required, and difficulty level.  Second, it would be useful to record information that help the analyst appreciate whether the step is required (see stopping rule).  For this, we might borrow properties from a training assessment technique know as the Difficulty, Importance, and Frequency (DIF) technique

  • This technique records the properties of each task to determine if the training needs of the person carrying out the task.  If we think of our website as providing "just-in-time" training, this might help us determine the best content to demonstrate the task to the customer.  Third, our website has options in how task information might be displayed (text, image, video).  If would be appropriate to have a property to record how the information will be displayed.

  • Properties: Expected time to complete, tools required, difficulty level of overall task, difficulty of individual task, importance, frequency, training content.

CONCLUSION

Congratulations! You know why you are performing your task analysis, you know how much detail you need to collect, and you have identified several task properties that you expect to be important. You are now ready to move on to the next step in Hierarchical Task Analysis, Information Collection.