Visualization of Enrollment Data using Chord Diagrams

L. Blasco-Soplon, J. Grau-Valldosera, J. Minguillón

Universitat Oberta de CatalunyaBarcelona, Spain

Context

● UOC: fully online open university– Learners with very diverse backgrounds

– No enrollment requirements● How many subjects?● Which ones?

– Recommendations from● Subject / course / degree planning (text / table based)● Mentor● “Common sense”

● First enrollment is known to be “critical”

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Learning Analytics

● Plenty of available data– Since 1994 (EHEA / Bologna degrees since 2008)

– Thousands of students each semester● Hundreds per degree

– Tens of thousands of subject combinations

– Academic performance● Subject level (PASS / FAIL)● Semester level (dropout)

● Can we do it better?

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Our proposal

● Analyze subject combinations– 2 x 2 contingency tables (PASS / FAIL)

● Visualize enrollment data– Intra-semester

– Inter-semester

● Provide better support (esp. 1st semester)– Learners: adjust enrollment

– Mentors: improve recommendations

– Degree managers: reduce dropout

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Available data (I)

● Paper: Business and Economics degree– From Spring 1999 to Spring 2011 (25 semesters)

– 21792 learners

– 501 different subjects

– 328467 subject enrollments

● New data from EHEA B&E degree (10 sems.)– 5930 learners

– 64 different subjects (59 in the 1st semester)

– 63460 subject enrollments (17610 in the 1st sem.)

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Available data (II)

● First semester only:– High dropout rates

– Are learners following institutional advice?

● 5698 learners take 2 or more subjects– 17378 subject enrollments

– 59 different subjects● 13 subjects: 90.6% of learners, 20 subjects: 95.5%

– 764 different subject combinations● 129 combinations: 90.0% of learners

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Chord diagrams

● Circular layout for representing relationships in matrix data as a graph– Segments: nodes

– Chords: edges

● Position, color, size● Popularized in 2007 by the

NY Times infographic Close-Ups of the Genome

by Giovanni Gherdovich

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Why chords?

● Explore new ways to provide support● Subjects can be sorted clockwise

– From most to least popular subject (size)

– Each subject can be independently colored according to its own PASS / FAIL ratio

● Subject combinations– Popularity + % of learners passing / failing one / two

subjects

● Available in D3.js– Interactivity “included” as part of the visualization

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Chord parametrization

● Number of segments– Number of chords grows quadratically

– Up to 10 segments looks fine, 6-8 seems optimal

● Segment colors– From red (FAIL) to green (PASS) through yellow

– Other thresholds can be used: [0, 0.4, 0.6, 1]

● Chord colors– Percentage of learners passing the two subjects

– Same red-yellow-green coloring

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Interactivity

● By default, show– Subjects

● Size: Importance (number of learners)● Color: Perfomance (PASS / FAIL ratio)

– Chords● Size: Number of learners taking such combination● Color: Number of learners passing the two subjects

● Interaction– On a segment: info about that subject and its

combinations with other subjects

– On a chord: info about that combinationVisualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Results

demoVisualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Conclusions

● Pros:– Compact visualization, nice aesthetics

● Easy to understand (green: OK, red: KO)

– Interactivity reduces data overload

– Easy integration into any web based system

● Cons:– 13 subjects generate 13*12/2=78 chords!

● Lack of data for non-common subjects / combinations

– Even the simplest visualization needs explanation

– What about blind / colorblind learners?

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Current and future work

● Evaluate the visualization compared to tables● Explore other visualization types

– Concentric chord diagrams (inter-semester)

– D3.js: parallel sets, ...

● Include other parameters– Learners' satisfaction

– Total time spent in the subject

– Weight as a inter-semester dropout factor

● Integrate it into the UOC enrollment process

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany

Thank you!

jminguillona[at]uoc[dot]edu

twitter/@jminguillona

http://bit.ly/1wcZCBk

Visualization of Enrollment Data using Chord Diagrams – GRAPP 2015, Berlin, Germany