The Keyboard StudyLecture /slide deck produced by Saul Greenberg, University of Calgary, Canada

Notice: some material in this deck is used from other sources without permission. Credit to the original source is given if it is known,

image soruce:

http://www.techradar.com/news/mobile-computing/tablets/best-tablet-keyboards-bluetooth-extras-for-ipad-android-or-windows-1130283

The Context

Company produces kiosks. • walk-up and use situations • only mouse input

• typically for navigating(e.g., menus)• but on screen keyboard for occasional text input

• end-customers vary in typing ability;• text entry must be quick to avoid line-ups• errors costly (e.g., banking)• small displays preferred due to cost, but…

The Idea

Qwerty vs Alphabetic, two sizes possible

The problem

Which is best?

What is the worst case?

Null Hypothesis 1

There is no difference between people's mouse-typing ability as measured in

speed (characters per second) and error rate (ratio of extra characters

typed over the minimum required) when using a

qwerty, alphabetic, or random layouts

on a simulated keyboard that issmall (measured as …) vs. large (measured as …) .

Experimental Design (ANOVA)

Type

Qwerty Alphabetic Random

Size Small S1(chars/sec)

S2(chars/sec)

…

Sn(chars/sec)

same same

Large same same same

Dependent variable: Characters/sec

Experimental Design (ANOVA)

Type

Qwerty Alphabetic Random

Size Small S1(errors)

S2(errors)

…

Sn(errors)

same same

Large same same same

Dependent variable: Errors (extra characters)

Null Hypothesis 2

People'styping speeds measured in characters per second

when touch-typing vs.mouse-typing

is not correlated on the 3 keyboards or theirsize

Experimental Design (Regression)

Mouse typing speed

Qwerty Alphabetic Random

Small Large Small Large Small Large

PhysicalTyping speed

S1(t1,t2)

S2(t1,t2)

…

Sn(t1,t2)

same same same same same

Issues ?

Design

Subject selection

Task

Ethics

Controls

Data collection / analysis

Issues ?

Design• random keyboard not really random• layout may affect results (guard zones, key size?)

Subject selection• range of expertise• not random• generalization

Task• copy typing vs. free form typing• was there sufficient practice, particularly with non-familiar keyboards? (realism)• learning curve (sentences same across all conditions)• sentence length (does it match real task?)• sentence type (punctuation, capitals, etc.)• fatigue, boredom• motivation to type

Issues ?

Ethics violations• no approval• power situation – had to be a subject

Controls • varying computers / screens / sound output• varying size of displays thus keyboard size• environmental conditions: rooms, furniture, computer placement

Data collection / analysis• extra step in moving data to spreadsheet error prone, tedious• errors – is this the best way to record it?• unclear when to discard data (e.g., above a certain error rate?)• unclear if errors due to keyboard (typing) or mis-reading / skipping

words in sentence

BUT

Many issues randomized across all conditions

Large effects may still emerge

Interpretation critical• generalization• applicability to the problem

revisit the scenario

In spite of problems, valuable as evidence• as interpreted by you

You know now

Designing even a simple study requires• intense planning and preparation• in-depth thinking of all aspects• pilots to debug problems• understanding limits• interpreting results as evidence for / against the

problem o limitations, implications, generalization, applicability, etc

Permissions

You are free:• to Share — to copy, distribute and transmit the work• to Remix — to adapt the work

Under the following conditions:Attribution — You must attribute the work in the manner specified by the author (but not in any way that suggests that they endorse you or your use of the work) by citing:

“Lecture materials by Saul Greenberg, University of Calgary, AB, Canada. http://saul.cpsc.ucalgary.ca/saul/pmwiki.php/HCIResources/HCILectures”Noncommercial — You may not use this work for commercial purposes, except to assist one’s own teaching and training within commercial organizations.Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

With the understanding that:Not all material have transferable rights — materials from other sources which are included here are cited Waiver — Any of the above conditions can be waived if you get permission from the copyright holder.Public Domain — Where the work or any of its elements is in the public domain under applicable law, that status is in no way affected by the license.Other Rights — In no way are any of the following rights affected by the license:

• Your fair dealing or fair use rights, or other applicable copyright exceptions and limitations;• The author's moral rights;• Rights other persons may have either in the work itself or in how the work is used, such as publicity or privacy rights.

Notice — For any reuse or distribution, you must make clear to others the license terms of this work. The best way to do this is with a link to this web page.