NUX Leeds - 28 August 2014 Designing usable number entry interfaces By Sarah Wiseman (@oopsohno) For years research has been conducted in the field of text entry, and has led to some innovative designs for alphabetic text entry interfaces, but little attention has been paid to the way we enter numbers. Number entry is a highly pervasive task, whether it be entering our PIN at an ATM, or dialing a phone number to entering in financial data or medical information. Sarah Wiseman investigates number entry interfaces, and looks at the important aspects to consider when designing them. http://nuxuk.org/2014/06/26/nux-leeds-28-aug-usable-number-entry

1. Number Entry Interfaces
Sarah Wiseman !
UCL Interaction Centre

2. Why Number Entry?
• Errors are important!
• Happens every day!
• So many interface options!
• Numbers are wicked cool

3. Mars Climate Orbiter

4. Mars Climate Orbiter
• Determine distribution of water on Mars!
• Monitor daily weather conditions!
• Determine temperature of atmosphere!
• Look for evidence of climate change

5. Mars Climate Orbiter
• Determine distribution of water on Mars!
• Monitor daily weather conditions!
• Determine temperature of atmosphere - REALLY HOT!
• Look for evidence of climate change

6. Mars Climate Orbiter
Lesson: !
Remember that numbers sometimes
mean something - not just random strings

7. Number Entry in the !
Medical Domain

8. Errors with Infusion Pumps

9. Errors in Design
12!

10. Errors with Numbers
compared to Text

11. Number Entry in the !
Medical Domain
Lesson: !
Remember that errors in number entry can
have serious consequences.

12. Humans checking for
number errors
Horse
Cow
Shepe
Donkey

13. Humans checking for
number errors
Horse
Cow
Shepe
Donkey
1111
1804
2911
3417

14. Humans checking for
number errors
Lesson: !
Number errors are really, really hard to spot

15. The design of the keypad

16. The Pushbutton phone

17. The Pushbutton phone cord

18. Making Number Entry Better

19. UCD in Number entry
• “I checked the user is able to press the button ok”

20. UCD in Number entry
• “I checked the user is able to press the button ok”!
• What numbers does the user actually want to
enter?

21. Benford’s Law

22. Blood Pressure Terminal
Digit
80
Percentage of occurrence 0
60
40
20
0 5 Even Number Odd number (not 5)
Terminating digit

23. Digits in the hospital
0 1 2 3 4 5 6 7 8 9 .
Digit
Frequency
0 500 1000 1500 2000 2500

24. Numbers in the hospital
Volume Frequency (%)
100 29.87
1000 9.97
50 9.07
500 6.36
20 3.81

25. Adapting interfaces

26. Optician’s Interface Design

27. Applying this to design
Faster Slower

28. Possible future design

29. Tailoring interfaces for
numbers
Lesson: !
Match the interface to the task it is being
used for, make the common numbers easy

30. Learning from text entry

31. Words and non-words
Last night the Great British Bake Off was shocking
little bit faster than
British was night Great shocking Last Off the Bake
faster than
Proum flim shoyar larof quask tullep exuge serah
faster than
Rteu fgdwww weqk sreemg wkgj gfmss mnoaish

32. Effect of words versus !
non words
Faster
Larger copy span
Larger look-ahead
I think the editors need to answer for their actions

33. Testing text entry interfaces

34. Testing number entry
interfaces
“We generated a set of random numbers and
asked users to enter them using the interface”

35. Similarity to numbers?
Pony ≠ Prfw
!
1066 ≠ 9379

36. Results of Familiarity
Interkeypress interval ms
400
350
300
250
200
Words Numbers
Familiar Non Familiar

37. Test with Realistic Numbers
Lesson: !
You wouldn’t test text entry with random
strings, don’t test number entry with them

38. Number Entry - !
Points to think about
• Number mean something, they aren’t just shapes!
• Number errors are big problem, and they are hard
to spot!
• Think about how your interface could be tailored,
keypad isn’t the only way!
• Don’t treat random numbers as though they are
representative - familiarity matters

39. Thanks, go and do really
good number entry stuff!
@oopsohno
www.swiseman.co.uk

40. • Deininger, R. L. (1960). Human factors engineering
studies of the design and use of pushbutton
telephone sets. Bell System Technical Journal, 39,
995–1012. !
• Retrieved from
http://www.vcalc.net/touchtone_hf.pdf