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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
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Number Entry InterfacesSarah Wiseman !UCL Interaction Centre
Why Number Entry?
• Errors are important!
• Happens every day!
• So many interface options!
• Numbers are wicked cool
Mars Climate Orbiter
Mars Climate Orbiter
• Determine distribution of water on Mars!
• Monitor daily weather conditions!
• Determine temperature of atmosphere!
• Look for evidence of climate change
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
Mars Climate Orbiter
Lesson: !
Remember that numbers sometimes mean something - not just random strings
Number Entry in the !Medical Domain
Errors with Infusion Pumps
Errors in Design
12 !
Errors with Numbers compared to Text
Number Entry in the !Medical Domain
Lesson: !
Remember that errors in number entry can have serious consequences.
Humans checking for number errors
Horse Cow
Shepe Donkey
Humans checking for number errors
Horse Cow
Shepe Donkey
1111 1804 2911 3417
Humans checking for number errors
Lesson: !
Number errors are really, really hard to spot
The design of the keypad
The Pushbutton phone
The Pushbutton phone cord
Making Number Entry Better
UCD in Number entry
• “I checked the user is able to press the button ok”
UCD in Number entry
• “I checked the user is able to press the button ok”!
• What numbers does the user actually want to enter?
Benford’s Law
Blood Pressure Terminal Digit
Perc
enta
ge o
f occ
urre
nce
0
20
40
60
80
Terminating digit
0 5 Even Number Odd number (not 5)
Digits in the hospital
0 1 2 3 4 5 6 7 8 9 .
Digit
Frequency
0500
1000
1500
2000
2500
Numbers in the hospitalVolume Frequency (%)
100 29.87
1000 9.97
50 9.07
500 6.36
20 3.81
Adapting interfaces
Optician’s Interface Design
Applying this to design
Faster Slower
Possible future design
Tailoring interfaces for numbers
Lesson: !
Match the interface to the task it is being used for, make the common numbers easy
Learning from text entry
Words and non-wordsLast night the Great British Bake Off was shocking
British was night Great shocking Last Off the Bake
Proum flim shoyar larof quask tullep exuge serah
Rteu fgdwww weqk sreemg wkgj gfmss mnoaish
little bit faster than
faster than
faster than
Effect of words versus !non words
Faster
Larger look-ahead
Larger copy span
I think the editors need to answer for their actions
Testing text entry interfaces
Testing number entry interfaces
“We generated a set of random numbers and asked users to enter them using the interface”
Similarity to numbers?
Pony ≠ Prfw !
1066 ≠ 9379
Results of Familiarity In
terk
eypr
ess
inte
rval
ms
200
250
300
350
400
Familiar Non Familiar
Words Numbers
Test with Realistic Numbers
Lesson: !
You wouldn’t test text entry with random strings, don’t test number entry with them
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
Thanks, go and do really good number entry stuff!
@oopsohno
www.swiseman.co.uk
• 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 fromhttp://www.vcalc.net/touchtone_hf.pdf
