Useability principles for evaluating a user interface

Name:

Date:

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Quick Questions

Shade in the A or B circle for each question.

1. A tester with low vision can read all text in a prototype because it uses large, high-contrast fonts. Which useability principle is being met?

A Engagement

B Accessibility

2. A user accidentally taps Delete and the app shows 'Undo' and 'Are you sure?'. Which principle does this support?

A Error tolerance

B Ease of learning

3. Which is the best evidence for rating ease of learning in a user trial?

A Time taken by new users to finish a task with no help

B The number of colours used in the design

4. A user trial shows 9 out of 10 testers completed the booking task correctly. Which principle is this evidence mostly about?

A Accessibility

B Effectiveness

5. Which statement is a useability rating backed by evidence?

A Error tolerance: 4/5, as 8 of 10 testers recovered from a wrong entry using the Undo button

B Error tolerance: 4/5, because I think the design looks good

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Error tolerance		AA usability principle: the interface prevents mistakes or helps users recover from them, for example with a confirm box or an undo option.
2Ease of learning		BThis is poor error tolerance. A confirm box such as 'Are you sure?' or an undo option should be added so accidental clicks can be recovered from.
3Accessibility is judged by checking whether people with different needs can use the interface, such as through readable text size and strong colour contrast.		CA usability principle: a new user can work out how to use the interface quickly, with little or no training.
4Effectiveness is rated with evidence from a user trial, such as how many testers completed the task correctly.		Dfont=('Arial', 18), fg='black', bg='white'
5Rating: Engagement = Good (no trial evidence given)		EThe rating has no evidence from a user trial. It should be supported, for example: 8 of 10 testers said the game was fun and kept playing.
6Delete button: deletes the record straight away, no warning		FTask completed: 9 of 10 testers = 90%

Definitions

useability principles

Fill in the Blanks

Complete each line of code by filling in the missing parts.

principle = "_____________" print(principle, "is for everyone")

rating = {} rating["_____________"] = "All 5 tasks done"

minutes = 4 __ minutes < 5: rating = "Good ease of learning"

principles = ["accessibility", "engagement"] ___ principle in principles: print(principle)

evidence = "4 of 5 users made no errors" _____("Error tolerance:", evidence)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A principle == 'engagement'

B rating = 3

C evidence = 'Stayed on task'

D print(principle, rating)

Question 2

A def rate(score)

B if score >= 4:

C return 'Good'

D return 'Needs work'

Question 3

A contrast_ok = False

B if contrast_ok:

C print('Easy to read')

D else

E print('Low contrast')

Question 4

A age = input('Age: ')

B while age.isdigit():

C print('Digits only')

D age = input('Age: ')

Question 5

A completed = 8

B total = '10'

C rate = completed / total * 100

D print(f'Completed: {rate}%')

Answer Key

Useability principles for evaluating a user interface

Section A: Quick Questions

B — Accessibility

A — Error tolerance

A — Time taken by new users to finish a task with no help

B — Effectiveness

A — Error tolerance: 4/5, as 8 of 10 testers recovered from a wrong entry using the Undo button

Section B: Match the Pairs

Error tolerance → A usability principle: the interface prevents mistakes or helps users recover from them, for example with a confirm box or an undo option.

Ease of learning → A usability principle: a new user can work out how to use the interface quickly, with little or no training.

Accessibility is judged by checking whether people with different needs can use the interface, such as through readable text size and strong colour contrast. → font=('Arial', 18), fg='black', bg='white'

Effectiveness is rated with evidence from a user trial, such as how many testers completed the task correctly. → Task completed: 9 of 10 testers = 90%

Rating: Engagement = Good (no trial evidence given) → The rating has no evidence from a user trial. It should be supported, for example: 8 of 10 testers said the game was fun and kept playing.

Delete button: deletes the record straight away, no warning → This is poor error tolerance. A confirm box such as 'Are you sure?' or an undo option should be added so accidental clicks can be recovered from.

Section C: Definitions

useability principles — Criteria for judging a prototype's interface: accessibility, effectiveness, error tolerance, ease of learning and engagement, rated using evidence from a user trial.

Section D: Fill in the Blanks

principle = "accessibility"
print(principle, "is for everyone")

rating = {}
rating["effectiveness"] = "All 5 tasks done"

minutes = 4
if minutes < 5:
    rating = "Good ease of learning"

principles = ["accessibility", "engagement"]
for principle in principles:
    print(principle)

evidence = "4 of 5 users made no errors"
print("Error tolerance:", evidence)

Section E: Spot the Error

A — == compares two values and does not store one. principle is never created, so the later print causes a NameError. It should be principle = 'engagement'.

A — A function definition must end with a colon. It should be def rate(score):.

D — else needs a colon after it to start its block. It should be else:.

B — The loop should repeat while the input is NOT valid, so the user gets another go after a mistake (error tolerance). Without not, it skips bad input. It should be while not age.isdigit():.

B — total is a string, so dividing by it causes a TypeError. The task completion rate (effectiveness) needs a number. It should be total = 10.