ETC5523: Communicating with Data

Effective data visualisation

Lecturer: Michael Lydeamore

Department of Econometrics and Business Statistics



Aim

  • Apply principles and practices for data visualisation that effectively and efficiently convey intended messages to viewers
  • Use data visualisation to create effective data stories

Why

  • “A picture is worth a thousand words”.
  • Data visualisation can make large, complex data more accessible, understandable and usable.

Data Visualisation

Data visualization is part art and part science. The challenge is to get the art right without getting the science wrong and vice versa.

– Claus O. Wilke, Fundamentals of Data Visualization

Role

  • A data visualization has to accurately communicate the data to the intended audience.
  • A data visualization must not mislead or distort information from the data.

💬️ Communicating with data visualisation

Communication

Effective data visualisation means to design your data plot to effectively use human visual system to improve cognition about a targeted information from the data.

  • I interchangeably use the terms data visualisation, plot, data plot, graphic, statistical graphic, and figure.

Birth place from the 2021 Australian Census

Birth place Count %
Australia 17,020,422 66.9
Not Stated 1,358,658 5.3
England 927,490 3.6
Other 759,173 3.0
India 673,352 2.6
China 549,618 2.2
New Zealand 530,492 2.1
Philippines 293,892 1.2
Vietnam 257,997 1.0
South Africa 189,207 0.7
Malaysia 165,616 0.7
Italy 163,326 0.6
Sri Lanka 131,904 0.5
Nepal 122,506 0.5
Scotland 118,496 0.5
Korea South 102,092 0.4
United States America 101,309 0.4
Germany 101,255 0.4
Hong Kong 100,148 0.4
Iraq 92,922 0.4
Greece 92,314 0.4
Pakistan 89,633 0.4
Lebanon 87,340 0.3
Indonesia 87,075 0.3
Thailand 83,779 0.3
Ireland 80,927 0.3
Iran 70,899 0.3
Fiji 68,947 0.3
Netherlands 66,481 0.3
Singapore 61,056 0.2
Afghanistan 59,797 0.2
Bangladesh 51,491 0.2
Canada 50,223 0.2
Taiwan 49,511 0.2
Brazil 46,720 0.2
Poland 45,884 0.2
Japan 45,267 0.2
Croatia 43,302 0.2
Egypt 43,213 0.2
North Macedonia 41,786 0.2
Zimbabwe 39,714 0.2
Myanmar 39,171 0.2
Cambodia 39,043 0.2
Turkey 38,568 0.2
France 36,019 0.1
Malta 35,413 0.1
Papua New Guinea 29,984 0.1
Chile 29,860 0.1
Wales 29,250 0.1
Samoa 28,107 0.1
Bosnia Herzegov 26,171 0.1
Mauritius 25,981 0.1

Birth place from the 2021 Australian Census

Which birth place is the third largest among people in Australia?

Birth place from the 2021 Australian Census

Can you read the labels without tilting your head?

Birth place from the 2021 Australian Census

What’s the data story?

India now third most common place of birth of Australian residents, census results show




  • The text on the bar shows the percentage out of 25,422,788 Australian residents born in that place.

  • There were 5.3% of Australian residents who did not state their birth place.

  • The top country of birth place is Australia with 66.9% of Australian residents born in Australia.

Story from The Guardian.

Another look

Data Story

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found.

– The Guardian

Birth place Count % Census Year
England 907,570 3.9 2016
New Zealand 518,466 2.2 2016
China 509,555 2.2 2016
India 455,389 1.9 2016
Philippines 232,386 1.0 2016
England 927,490 3.6 2021
India 673,352 2.6 2021
China 549,618 2.2 2021
New Zealand 530,492 2.1 2021
Philippines 293,892 1.2 2021

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found

Does this show that India overtook China and New Zealand?

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found

Should we show percentage instead of counts?

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found

The legend and the line order is different…

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found

Maybe we can put the labels directly in the plot?

India has overtaken China and New Zealand to become the third largest country of birth for Australian residents, 2021 census data has found

What plot type to use?

🛒 Data Visualisation Catalogue

Non-exhaustive

Composite plots

  • Your data plot may be made from multiple plot types:

Composite plots

  • Your data plot may be composed of multiple subplots:

Why is a 3D pie chart considered a “bad plot”?

What about 2D pie charts?

Pie charts are a very bad way of displaying information. The eye is good at judging linear measures and bad at judging relative areas. A bar chart or dot chart is a preferable way of displaying this type of data.

  • This comes from empirical research of Cleveland & McGill (1984) among others.

Elementary Perceptual Tasks

Non-exhaustive

Retrieving information from graphs

Of the 10 elementary perception tasks, Cleveland & McGill (1984) found the accuracy ranked as follows…

Rank 1

Example

Rank 2

Example

Rank 3

Example

Rank 4

Example

Rank 5

Example

Rank 6

Example

Preattentive processing

  • Viewers can notice certain features are absent or present without focussing their attention on particular regions.
  • Which plot helps you to distinguish the data points?

Gestalt Principles

  • “Gestalt” is German for form or shape.
  • A set of laws to address the natural compulsion to find order in disorder by perceiving a series of individual elements as a whole.

Law of Proximity

  • By placing elements closer together, it makes it easier for you to group elements together as well as make comparisons.

Can you tell which birth place have more women than men amongst the Australian residents?

Law of Proximity

Data story

Census 2021 shows far more women born in Phillipines and China migrate to Australia than men born in their respective countries, whilst more men born in India migrate to Australia than women born in India.

Law of Similarity

  • When objects share similar attributes, they are perceived as being part of the same group.

Notice that the countries are colored by their continent (Europe, Asia, and Oceania).

Law of Closure

  • Objects collected within a boundary-like structure are perceived as a group.

Color space

Zeileis, Fisher, Hornik, Ihaka, McWhite, Murrell, Stauffer, Wilke (2019). colorspace: A Toolbox for Manipulating and Assessing Colors and Palettes. arXiv 1903.06490

Zeileis, Hornik, Murrell (2009). Escaping RGBland: Selecting Colors for Statistical Graphics. Computational Statistics & Data Analysis 53(9) 3259-3270

Qualitative palettes

  • Designed for categorical variable with no particular ordering
colorspace::hcl_palettes("Qualitative", plot = TRUE, n = 7)

Sequential palettes

  • Designed for ordered categorical variable or number going from low to high (or vice-versa)
colorspace::hcl_palettes("Sequential", plot = TRUE, n = 7)

Diverging palettes

  • Designed for ordered categorical variable or number going from low to high (or vice-versa) with a neutral value in between
colorspace::hcl_palettes("Diverging", plot = TRUE, n = 7)

Colorblindness

Colorblindness affect roughly 1 in 8 men.

Check your color choices using the colorblindr package or otherwise.

Week 6 Lesson

Summary

  • We went some examples of constructing data plots to illustrate your data story
  • We looked at some plot types and elementary perceptual tasks
  • We examined the empirical results of the information retrieval from elementary perceptual tasks
  • We studied at some cognitive concepts, like preattentive processing and Gestalt principles, for data visualisation
  • We saw the different types of color palettes and considered color choices for colorblind audiences

Week 6 Lesson

Resources

ETC5523 Week 6