Plain text version of slides from session on Data Visualisation and Accessibility for Analysis in Government Month 2022

Slide 1

Data Visualisation and Accessibility, Analysis in Government Month 2022

Slide 2

Welcome

Slide 3

Accessibility legislation

Slide 4

All content published on public sector websites must meet the level A and AA success criterion in the Web Content Accessibility Guidelines 2.1.

Slide 5

The following accessibility success criterion impact on colours of chart elements and the use of coloured text for chart labels:

Contrast (minimum): The visual of presentation text and images of text has a contrast ratio of at least 4.5 to 1.

Non-text contrast: all adjacent colours used in graphics need at least a 3 to 1 contrast ratio. This applies unless the presentation is “essential” for communicating a message.

Slide 6

The following accessibility success criterion impact on use of chart legends:

Use of colour: colour is not used as the only visual means of conveying information.

Sensory characteristics: Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, colour, size.

Slide 7

The following accessibility success criterion impact on alternative text:

Non-text content: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose.

The following accessibility success criterion impact on placement of chart titles, source information and footnotes:

Images of text: text is used to convey information rather than images of text, except if the image is customisable or essential.

Slide 8

What to supply with all charts:

  • Titles
  • Alternative text
  • Source
  • Data download
  • Footnotes

Slide 9

Example

  • Can I have some more? Oliver stays at the top

This is the headline title of the chart, it lives in the body text of the page.

  • Figure 1: Top 10 most popular names for baby boys, England 2020

This is the statistical heading for the chart, it also lives in the body text of the page

This is followed by an image of the chart in the SVG format. The chart is marked as decorative so it will be ignored by screen reader software.

  • This bar chart shows Oliver is the most popular name given to baby boys in England in 2020. A total of 4,017 boys were named Oliver, followed closely by George, Arthur, Noah, and Muhammad which were all given to over 3,500 babies. The next most popular were Leo, Oscar, and Harry (all given to over 3,000). Archie and Henry completed the top 10 (both given to over 2,500).

This is the alternative text to the chart image. It gives the equivalent experience to looking at the chart image. It lives in the body text of the page and it immediately follows the chart image.

This is the link to the data source for the chart.

This is an accessible data download of the data used in the chart.

Slide 10

Formatting:

  • Colours
  • Simplicity
  • Labels
  • Grid lines
  • Annotations
  • Tick marks

Slide 11

This chart shows the three colour palette tables set out in the ‘Data visualisation: colours’ guidance.

Slides 12, 13, 14, 15, and 16

These slides summarise the content in the formatting section of the ‘Data visualisation: charts’ guidance.

Slide 17

Bar charts:

  • Bar vs. Pie
  • Gaps
  • Breaking y-axis
  • Time series
  • Value labels
  • Stacks and clusters

Slides 18, 19, 20, 21, 22

These slides summarise the content in the bar charts section of the ‘Data visualisation: charts’ guidance.

Slide 23

Stacks and clusters:

  • Part to whole
  • Limit on categories
  • Order
  • Negative values
  • Colour contrast
  • Gaps
  • Legends

Slide 24

Line charts:

  • Colours
  • Labelling
  • Max of four
  • Alternative approaches
  • Breaking the y axis
  • Context

Slide 25, 26, 27, 28, 29 and 30

These slides summarise the content in the line charts section of the ‘Data visualisation: charts’ guidance.

Slide 31

Pie charts

  • When to use
  • Colours
  • Order
  • Labels

Slide 32

Testing:

  • Tweet
  • Twitter poll
  • Basecamp
  • Colleagues
  • Champions

Slide 33

Demo 1

Slides 34, 35, 36, 37, 38, 39, 40, 41 and 42

These slides summarise Example 1 on the ‘Data visualisation: examples’ guidance.

Slide 43

Demo 2

Slides 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 and 56

These slides summarise Example 2 on the ‘Data visualisation: examples’ guidance.

Slide 57

Thank you

@statshan