Does Size Matter? Investigating the impact of mobile phone screen size on users’ perceived usability, effectiveness and efficiency Dimitrios Raptis, Nikolaos Tselios, Jesper Kjeldskov, Mikael Skov PhD Fellow, Computer Science Department, Aalborg University
19
Embed
Does Size Matter? Investigating the impact of mobile phone screen size
Does Size Matter? Investigating the impact of mobile phone screen size on users’ perceived usability, effectiveness and efficiency
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Does Size Matter? Investigating the impact of mobile phone screen size on users’ perceived usability,
effectiveness and efficiencyDimitrios Raptis, Nikolaos Tselios, Jesper Kjeldskov, Mikael Skov
PhD Fellow, Computer Science Department, Aalborg University
our idea
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
does the size of the screen affect users’ interaction with a mobile device when they use a mobile application?
is this effect significant?
if yes is this effect consistent for various screen sizes?
2 of 17
research hypotheses
goal: measure the effect of a mobile phone’s screen size on users’ perceived usability, efficiency and effectiveness
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
H 1: the mobile phone’s screen size will have an effect on participants’ perceived usability (a larger screen will increase the perceived usability ratings).
H 2: the mobile phone’s screen size will have an effect on participants’ task completion times (a larger screen will increase efficiency).
H 3: the mobile phone’s screen size will have an effect on participants’ task completion rates (a larger screen will increase effectiveness).
3 of 17
parameters can that affect (perceived) usability
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
attractiveness
effectiveness
efficiency
prior experience
brand
prior usage perceptions
4 of 17
device/application
device and application selection
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
3 devices of the same brand, with identical visual design
IMDB 2.3.1, an information seeking application
5 of 17
Model Size (mm) Scr.Size
Resolution
Galaxy Ace 112.4x59.9x11.5 3.5in 320*480
GalaxyNote 145.8x66.1x8.5 5.3in 800*1280
Galaxy SII 125.3x66.1x8.5 4.3in 480*800
D i m i t r i o s R a p t i s , h t t p : / / p eo p l e . c s . a a u . d k / ~ r a p t i s
pre-experiment actions
aim: to provide an as similar as possible interface on three devices with similar hardware performance
we installed the same Android versions, same launcher, same theme, same keyboard.
we locked the screen orientation
we underclocked the CPUs (800Mhz)
6 of 17
experiment
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
finding:a significant gain on efficiency occurs when the screen size increases more than 4.3in
10 of 17
the effect of screen size on efficiency (H2)
One way between subjects ANOVA
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
we observed a significant effect of screen size on efficiency for:
Task 3, F(2, 57)= 6.016, p=.004**
Task 5, F(2, 57)= 4.559, p=.015*
finding:not all information seeking tasks benefit from a larger display, but only the tasks that are not easy and require a significant amount of scrolling.
H 2 was confirmed11 of 17
the effect of screen size on effectiveness (H3)
CHI Square tests per task (completion rate)
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
H 3 was rejected as there was not observed any significant effect of screen size on effectiveness
12 of 17
D i m i t r i o s R a p t i s , h t t p : / / p eo p l e . c s . a a u . d k / ~ r a p t i s
other important observed effects a significant high correlation between adjective
rating and SUS score (Pearson’s r=0.679, p<.001**)
a significant modest correlation between total task completion time and SUS score (Pearson’s r=-0.357, p=.005**)
a significant difference between the participants’ SUS rating with prior experience (44 participants) and without experience (16 participants), two tailed T-test, t=2.141, p=.04*
13 of 17
findings
everyday usage
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
mobile users:
when they interact with a device and perform information seeking tasks, they will be more efficient using a device with a screen larger than 4.3in.
designers:
they should consider alternative ways to minimize scrolling
in tailored applications for specific contexts they should consider to select devices with screens larger than 4.3in
14 of 17
findings
practitioners/researchers
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
researchers and practitioners that measure perceived usability through SUS will not observe any differences if they evaluate an application on devices with different screen sizes.
researchers and practitioners that assess usability through usability metrics, such as effectiveness and efficiency, they will observe that larger screens will lead to higher efficiency.
15 of 17
future work
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
study the effect of screen size on an expanded set of tasks, such as map navigation, video browsing, etc.
expand the devices in order to measure if and when the identified positive effect on efficiency stops/declines.
investigate in detail if the participants of a mobile usability laboratory evaluation are influenced regarding their SUS scores, when they are asked to evaluate an application using a mobile device that has the same screen size as the one they own.
study the screen size effect over time, in real world conditions as the familiarity with a device increases.
16 of 17
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
Thank you!!
17 of 17
D i m i t r i o s R a p t i s , h t t p : / / p eo p l e . c s . a a u . d k / ~ r a p t i s
device familiarity
a significant effect from a two-way ANOVA between favorite/owned screen size (F(3, 48) = 5.887, p = .002**) and screen size F(2, 48) = 6.525, p = .003**) on SUS score, (F(6, 48) = 3.663, p = .004**)
18 of 18
limitations
D i m i t r i o s R a p t i s , h t t p : / / p e o p l e . c s . a a u . d k / ~ r ap t i s
the test application’s interface was identical, but not exactly the same on all three devices
the Galaxy SII and Note had the same AMOLED screen, but not the ACE
we did control for screen brightness but not accurately