The apprehension of overlaidinformation in a Web map

Dzenan Dumpor and Terje MidtbøNorwegian University of Science and Technology

«Mashup» – from music production

Map mashup

Cluttering problem

Map mashup - contrast

Research questions

• How do basemaps influence how fast participants solve tasks related to the overlaid data?

• How will the participants experience in using maps impact their performance?

• Are there any differences between genders when solving the same tasks?

Web-based experiment

• Three different basemaps (from ESRI)• Three different geometric enteties (points,

lines and areas)• Four different colours for overlaid

information

The basemaps

Thopographic map World Imagery Dark Grey Canvas

Three types of tasks

Point - point Point - line Point - area

Qualitative colour scheme

The Web application

Questions - examples

Point - point:• Which point is closest to a school? • Which point is closest to a medical-centre? • Which point is in total closest to both a school and a medical-centre? Point - line:• Which path starts at a school and crosses the river? • Which path goes from a plaza to a market? • Which path passes the largest number of markets on its way?Point - area:Which area contains six schools and only one medical-centre? Which area contains most markets? Which area does not contain a plaza?

The experiment

1. Information on welcome page2. Tutorial, one for each geometrical

combination3. Experiment: Three basemaps for each

geometrical combination4. General questions

Measured elements

• Time elapsed on tasks• All map operations (e.g., zoom/pan)• The basemap used for the task• Correct or wrong answer• General information

• Sex• Age• Used device (tablet or computer)• Experienced map user?• Assessment of concentration during experiment

Experiment – two parts

Initial experiment• All geometrical combinations involved• 60 male and 32 female participants

Focused experiment• Most interesting geometrical combination• 270 male and 80 female participants

Results from initial experiment

Topographic World Imagery Dark-Grey

Point/point tasksNo. of observationsSample mean (sec.)Standard dev. of x (s)

2948.321.1

3145.718.8

3042.714.8

Point/line tasksNo. of observationsSample mean (sec.)Standard dev. of x (s)

3257.019.9

2866.933.1

3063.027.0

Point/area tasksNo. of observationsSample mean (sec.) Standard dev. of x (s)

2950.518.0

3163.839.5

3049.730.6

Results from initial experiment

H0: m1 = m2 =….= mkH1: Minimum two of the mk's are different

Confidence interval of 95%:

ANOVA for point/point tasks F-value: 0.67Critical value: 3.10

H0 acceptedNo significant differences

Kruska-Wallis for point/line tasks H-value: 0.89Critical value: 5.99

H0 acceptedNo significant differences

Kruska-Wallis for point/area tasks H-value: 4.75Critical value: 5.99

H0 acceptedNo significant differences

Focused experiment - change

Results from focused experiment

Total Male Female Withexperience

Withoutexperience

No. of observationsSample mean (sec.)Standard dev. of x (s)

27060.030.8

19061.633.5

8056.122.7

13965.835.4

13153.823.4

Results from focused experiment

Topographic World Imagery Dark Grey

Point/areatasksNo. of observationsSample mean (sec.)Standard dev. of x (s)

9068.738.8

8956.126.4

9155.222.9

Male participants onlyNo. of observationsSample mean (sec.)Standard dev. of x (s)

6373.442.2

6355.427.1

6456.125.2

Female participants onlyNo. of observationsSample mean (sec.)Standard dev. of x (s)

2757.526.3

2657.824.3

2751.716.1

H0: medianA = medianBH1: medianA <> medianB

Results from focused experimentMann-Whitney U testConfidence interval of 95%

Differences between genders Z-value: 0.54Critical value: 1.96

H0 acceptedNo significant differences

Differences between experienced and non-experienced map users

Z-value: 3.39Critical value: 1.96

H0 rejectedSignificant differences

H0: m1 = m2 =….= mkH1: Minimum two of the mk's are different

Results from focused experimentKruskal-Wallis one-way analysis of varianceConfidence interval of 95%

Differences between basemaps, all participants

H-value: 10.0Critical value: 5.99

H0 rejectedSignificant differences

Differences between basemaps,male participants only

H-value: 13.9Critical value: 5.99

H0 rejectedSignificant differences

Differences between basemaps,female participants only

H-value: 0.24Critical value: 5.99

H0 acceptedNo significant differences

Differences between basemaps,non-experienced map users

H-value: 14.32Critical value: 5.99

H0 rejectedSignificant differences

Conclusions• The background map does matter when studying

overlaid information• Experienced map users spent longer time than non-

experienced map users. • The time used for solving the tasks was significantly

higher when using topographic maps (richer on details)• Female participants seems to handle different

backgrounds more equally• Dark grey basemap gives good contrasts together with

coloured symbols, and appears to be a good choice