Safety

Question 1

Errors in UI

Answer 1

• Excel carries formulas that must be entered with Ctrl Shift Enter not just Enter, every other edit you do is terminated by enter
• Caps Lock - when it’s enable on a keyboard, the letter keys produce uppercase letters
• The same action has diff meanings
• If a user means to type lowercase letters but doesn’t notice that caps lock is enabled
• Failing to correctly evaluate state of interface

Question 2

Error Prevention: Safety from Errors 1

Answer 2

• Avoid actions with similar descriptions: different things should look and act different
• Keep dangerous commands away from common ones e.g. Outlook 2003

Question 3

Safety from Errors 2

Answer 3

• Eliminate the modes but not always possible, modes do have some uses like making command sets smaller
• Increase visibility of mode:
• Status indicators must be visible in the users locus of attention
• Spring loaded mode:
• Shift key is spring loaded ver of uppercase mode
• Drag and drop

Question 4

Confirmation Dialogs

Answer 4

• Unfortunately common strategy for error prevention
• Not a good idea since efficiency is decreased because two buttons need to be pressed to confirm an action
• Slow downs UI
• Reversibility (undo) is better solution than confirmation

Question 5

User Control and Freedom

Answer 5

• Good UIs are explorable
• Learning by doing:
• An UI should encourage exploration making things more visible and consequences of errors less severe
• An easy, obvious way to get back to default/home view
• User should have ultimate control

Question 6

Clearly Marked Exits

Answer 6

• The simplest kind of user control is veto (the ability to cancel an operation
• Long operations should be cancellable
• All dialogs should have a cancel button

Question 7

Never Ask Me Again

Answer 7

• Many interfaces interrupt users with questions:
• If the answer is always the same, its inefficient
• Does improve user control

Question 8

Error Messages: Writing Error Message Dialogs

Answer 8

• Best error message is none at all

- Errors should be prevented e.g. not allowing a user to type in letters in a number field

Question 9

Error Messages: Be Precise and Comprehensible

Answer 9

• Be precise:
• Find out what’s really wrong and display a targeted message e.g. Line too long
• User can adapt
• Restate user’s input
• e.g. Cannot open file named paper.doc instead of Cannot open file so problem is detected immediately
• Speak the user’s language
• Not FileExceptionNotFound
• Hide technical details until requested

Question 10

Error Messages: Suggest Reasons and Solutions

Answer 10

• Give constructive help not just reporting the rror

- Why error occured and how to fix it

Question 11

Be Polite

Answer 11

• Be polite lol

- S