Quiz Number 4

SWE 432, Fall 2009
October 1

  1. Classify (and justify) each of the following as either revenue or excise tasks:
    • Saving a document to a file.
      Answer: Excise. Naturally, a user wants a document to be available later - preferably in all (or most) states of editing. Current Office products support some parts of this notion, but not all. For example, saving a document makes it impossible to see prior version (they are "written over" - another excise notion.) Note that selecting a particular version of a document - for example to send to someone else - is a revenue task, not an excise task. There is no way for the system to know which version (other than to guess the current) is correct. Further, users often don't want to share editing history with the recipient of a document. (This can be embarrassing!)
    • Composing a paragraph.
      Answer: Revenue. Sadly, composing original material is not a capability of current systems - nor is it likely to be. However, there have been some hilarious attempts in this direction.
  2. What does Nielsen mean by "Minesweeping". Is it a good or a bad thing?
    Answer: Minesweeping is dragging the cursor to look for clickable items hidden in a page. It is definiteately a bad thing; clickable items should be clearly clickable.
  3. What is an "Affordance", and what does it have to do with web usability?
    Answer: An affordance is whatever can be done with an object. Links have the affordance of clickability. Perceived affordance is crucial in that users will try to click items that afford clickability, and users will ignore items that don't.
  4. Suppose a web form accepts a number of fields. Suppose it accepts a license number as a letter followed by 8 digits: A12345678.

    Suppose the user replaces the first digit with a letter: AB1234567
    • Give an example error message that is not specific.
      Answer: Incorrect entry on form submission. (Not specific to license field.)
    • Give an example error message that is not constructive.
      Answer: License number format wrong. (Not constructive about what the correct form is.)
    • Give an example error message that is hostile.
      Answer: User Error. (Blames the user)
    • Give an example error message that is specific, constructive, and not hostile.
      Answer: License number is one character followed by 8 digits.
    Discuss the following options for having the user repair the error:
    • Blank out all fields, including license, and have user start over.
      Answer:
      Blanking out all fields, including the license field, is not constructive. Doing so breaks the user's work flow, causes the user to enter information that the application already knows, and causes user frustration.
    • Show the user a blank license field to fill in.
      Answer:
      Showing a user a blank field still requires the user to retype part of the license. Also, not showing the user what he or she actually typed is not constructive, because it does not show him or her the mistake made on initial entry.
    • Show the user the license field as entered, and allow user to edit.
      Answer:
      This is a constructive approach. Even better would be to highlight the error (for example, provide a colored background for the missing digit).