2004

• Should the assignments follow SYDE style guidelines, including the double spacing and font size restriction?

• It is recommended to use those guidelines. 

2003  

Fault Tree Analysis

• Why do we do the Fault Tree Analysis in this format? The same information could be simply listed in a table.
• Are single causes in the FTA okay, or should they be grouped into a single event?
• How are FTA events defined? If faulty maintenance is caused by a management policy, should that policy be somehow included in the FTA?
• How important is it that our FTAs exactly match yours (at least the main trees)?
• Should the FTA be in chronological order?
• Does an FTA just look at things that could go wrong with the object, or also things that could go wrong with the user interacting with the object?
• If the user is involved, how to we include failing to identify what to do next? Is this an event?
• Should cognitive and motor events be mentioned? eg. Failing to move fast enough to press a button.

Action Cycle

• What is the difference between Act and Sequence?
• What is the difference between Evaluation and Interpretation?
• How many iterations of the Action Cycle should we do?
• Should we include design problems in the Action Cycle? Do we analyse the perfect case or a screwed up case?
• How will the Action Cycles be marked?
• (June 7) What's the difference between Intention and Goal?
• (June 7) What's the difference between World, Perception and Interpretation?
• (June 7) What's the difference between a gulf of evaluation and a gulf of execution? Do they both occur or is it usually just either one or the other?

Midterm Exam

• Since the midterm is open-book, are we allwed to have side notes written into the columns or use post-it notes with reminders written on them?
• (June 7) Will we have a choice between using the action cycle and HTA or OOTA? Are we required to know HTA or OOTA?
• (June 7) With the many assigned chapters from Wickens, there is a fair bit of material that hasn't been covered in lectures. For the midterm, should I be focusing more on the material taught in lectures or the material covered in the text? It's important that I take note of the material that hasn't been mentioned in class?
• (June 7) Can I get your advice as to a good suggestion of the division of study time between Wickens, Stories from Set Phaser on Stun and Lecture notes? Ie... 1/3 time each, or 50% lecture notes, 25%Wickens, 25% case studies?

Fault Tree Analysis

• Why do we do the Fault Tree Analysis in this format? The same information could be simply listed in a table.
  The tree shows things more visually, its also how it is always done. If you do a more complex analysis with multiple "branches" it would not be possible to do it in a table. The coffee pot example in class is an example of a FTA with multiple branches.



• Are single causes in the FTA okay, or should they be grouped into a single event? For example, in the Bhopal case study, the flare tower wasn't working because an essential pipe was missing.
  Its enough to say that the "flare tower was not working". Saying "pipe missing from the flare tower" would be acceptable too. They are really the same event, just different levels of detail. It will be enough in the exams to work out 1 branch of the FTA successfully.



• How are FTA events defined? In the same case study, the pipe was missing because it was removed (a normal maintenance event) and not replaced (an abnormal non-event). If faulty maintenance is caused by a management policy, should that policy be somehow included in the FTA?
  Faulty policies are definitely factors in accidents. A fault tree analysis is nothing more than a chain of events though. Things which are overall factors are not included e.g." worker was tired/stressed/not trained". These are not events. The FTA must focus on what actually happened, and generally on things or conditions that had to be proximate in time for the accident to continue. Look for things like - poisonous gas and broken safety system (seen in Bhopal). "jeans and interview" seen in the coffee pot example. "worker asleep and alarm goes off". Always look for two things that happened at the same time.
  "worker fatigued" is a factor, "worker asleep at 9:00pm" is an event. Events are defined by time.
  We'll be looking at other ways of examining the overall factors that also contribute to accidents. Often we work from the FTA to examine these asking questions like: - why was the worker asleep? - why was the pipe not replaced in the flare tower? These questions can pull out policy and management issues.



• How important is it that our FTAs exactly match yours (at least the main trees)?
  Fault trees are evaluated on
  1. correct choice of and/or.
  2. understanding what an event is.
  3. understanding the sequence of events that occurred.
  If you missed an event in the sequence you would lose a mark for that event. If your tree contained factors and not events you would lose many marks. Saying "pipe missing from flare tower" or "flare tower not working" would both get marks since they both identify the event, and indeed, an important event in the accident.



• Should the FTA be in chronological order?
  Absolutely. The FTA shows a sequence of events, so chronological order is required.



• Does an FTA just look at things that could go wrong with the object, or also things that could go wrong with the user interacting with the object?
  The analysis looks at events with the object. If the user initiates an event then it can go in the analysis. The description though must be event based e.g. "machine in high radiation mode" and "activation button pressed."
  Note that this describes the state and the events of the object.



• If the user is involved, how to we include failing to identify what to do next? Is this an event?
  No, that is not an event.



• Should cognitive and motor events be mentioned? eg. Failing to move fast enough to press a button.
  You can include this as an event by wording it differently: "button-active time expires."

Action Cycle

• What is the difference between Act and Sequence?
  "Sequence" refers to the sequential list of actions that should have happened.
  "Act" is the physical doing of the actions (i.e. what actually happened).
  Sometimes mistakes are made when the action is physically performed (as in the lost cord). Sometimes the action can not be physically performed, it may require too much strength, or the control may be out of reach, etc.



• What is the difference between Evaluation and Interpretation?
  Interpretation is how you interpret, or what meaning you derive from, your perception of the world. Evaluation is simply the decision of whether or not your goal was met. If you're changing a light bulb, you might perceive that the room is brighter when you turn the new bulb on. You could interpret this perception to mean that the new bulb works and has been installed correctly. Then you would evaluate your action and decide that yes, you have successfully achieved your goal of changing the light bulb.



• How many iterations of the Action Cycle should we do?
  ONLY ONE!! (1)
  Make sure on this that you don't get trapped into doing 2 cycles.
  You should go through the cycle stage by stage, once. At each stage discuss what happened. At the part that it breaks down you should say, "xxxx should have happened but instead yyyy happened." Then you should continue along the cycle, following what happened with yyyy.



• Should we include design problems in the Action Cycle? Do we analyse the perfect case or a screwed up case?
  Most often, you will be asked to do an action cycle on a case study. There will always be a breakdown in one of the stages. See above answer for more information.



• How will the Action Cycles be marked?
  Action Cycles are marked as follows:
  • clear understanding of what each stage means
  • application of the stage to the current case
  • understanding of where things break down
  HINT: Don't forget to describe what happened "in the WORLD." This is a common error.



• What's the difference between Intention and Goal?
  - Goal is the overall goal that you are trying to achieve (eg. get more light while reading at night)
  - Intention is a high-level sequence of events that will allow you to reach your goal (eg. push the switch on the lamp)
  - Sequence is the detailed list of events that you should do to make your intention happen (eg. how to move your body, how to stretch to reach the light switch, how to extend your finger to push the button without knocking over the lamp)
  The above is from Norman, p. 46.
  - Execution is then the actual sequence of events that a person has taken (eg. you get up from your chair, trip on the lamp's power cord and accidentally knock the lamp over)



• What's the difference between World, Perception and Interpretation?
  - World is what actually happens (eg. the lamp breaks)
  - Perception is the signals that you get from the world (eg. the lamp looks and feels broken)
  - Interpretation is what you interpret those signals to mean (eg. since the lamp looks and feels broken, it must be broken)
  Finally, Evaluation is simply whether you achieved your goal (eg. did you get more light?). In this case no, you did not achieve your goal.
  



• What's the difference between a gulf of evaluation and a gulf of execution? Do they both occur or is it usually just either one or the other?
  A gulf of evaluation occurs between the world and evaluation. Can the user perceive enough signals so that the state of the world is defined? Are those signals clear enough that the user can interpret them correctly?

  A gulf of execution occurs between the goal and the world. Can the user easily formulate a correct intention to achieve the stated goal? Is the sequence of actions that should be taken to achieve the intention clear? Does the user's execution match the sequence of actions or does the user deviate from what should have been done?

  They can occur together or separately.

Midterm Exam

• Since the midterm is open-book, are we allowed to have side notes written into the columns or use post-it notes with reminders written on them?
  NO notation or indexing tools in your text books. Only HIGHLIGHTING. You may not have:
  • worked assignment problems
  • worked web assignments
  • notes from the class presentations
  
  We do check the books in the exam. If a book is questionable, we take it away and give you one of our books.




• With the many assigned chapters from Wickens, there is a fair bit of material that hasn't been covered in lectures. For the midterm, should I be focusing more on the material taught in lectures or the material covered in the text? It's important that I take note of the material that hasn't been mentioned in class?
  Focus on the material that has been emphasized in the lectures.



• Can I get your advice as to a good suggestion of the division of study time between Wickens, Stories from Set Phaser on Stun and Lecture notes? Ie... 1/3 time each, or 50% lecture notes, 25%Wickens, 25% case studies?
  I would concentrate on the lecture notes, the case studies, and the web assignments. Think of how the lecture notes can be applied to the case studies.