Data visualisation: examples

Policy details

Metadata item Details
Publication date:19 May 2022
Author:Analysis Function Central Team
Who this is for:People in government who create charts
Type:Guidance
Contact:Analysis.Function@ons.gov.uk

Introduction

This guidance item will be used as a place to show examples of using our data visualisation guidance with real-life charts and tables.

Example 1

Publication: Adult social care monthly statistics, England: April 2022

Original chart: Figure 10 on number of Covid-19 tests carried out in care homes 

The original chart is an image of a line chart with four lines. It is in PNG format. Each line is labelled using text of the same colour. There are no gridlines on the chart image. Some dotted lines are used to mark specific events.  Some of these dotted lines overlap the series labels.

Our version: option a

Slight increase in Covid-19 tests among care home staff and residents

Figure 1a: number of rapid lateral flow and PCR tests conducted in care home staff and residents, weekly, England, October 2021 to March 2022

Large version of a chart zoomed to the time period of interest with use annotations to add context.

The line chart shows a slight increase in the number of PCR and rapid lateral flow tests carried out among care home staff and residents in March 2022. This follows a big decrease in recent months. The changes are partly, but not fully, explained by changes to the testing regulations. See table 6 in this publication for full details on changes in testing regulations.

Source: NHS Test and Trace

Download the data for figure 1a (ODS, 10KB) 

Summary of edits

  • Focused in on the end of the time series as that is what the narrative talked about
  • Used the colours suggested in our colours guidance
  • Increased the thickness of the lines
  • Labelled the lines with black text – black text is preferable to coloured text in general
  • Placed line labels on the edge of the chart so nothing in the chart overlaps the labels
  • Added annotation to describe the changes in testing regulations that may have impacted the data
  • Annotation is presented in text boxes with a white fill so the grid lines do not show through
  • Used the SVG format for the image of the chart so it retains clarity even when you zoom in on the image
  • Added tick marks on x-axis
  • Added a descriptive alternative text under the chart
  • Created an accessible data download of the data used in the chart

Demonstration of making Figure 1a

A video demonstration of making Figure 1a using Excel and PowerPoint will be posted on our Analysis Function YouTube channel soon.

Our version: option b

Slight increase in Covid-19 tests among care home staff and residents

Figure 1b: number of rapid lateral flow and PCR tests conducted in care home staff and residents, weekly, England, October 2021 to March 2022, 

Large version of a chart zoomed to the time period of interest with annotated letters which relate to letters in the body of the text.

The line chart shows a slight increase in the number of PCR and rapid lateral flow tests carried out among care home staff and residents in March 2022. This follows a big decrease in recent months. The changes are partly, but not fully, explained by changes to the testing regulations.

The chart has dotted lines which relate to changes in testing regulations.

From 7 June 2020 staff in care homes were required to do weekly PCR tests and two weekly rapid lateral flow tests. Residents were required to do monthly PCR tests. There were also PCR tests for anyone with symptoms.

  • Annotation A = from 15 Dec 2020 the number of mandatory weekly lateral flow tests for staff increased to three
  • Annotation B = from 11 Jan 2021 there was no need for a confirmatory PCR after positive lateral flow test
  • Annotation C = from 16 Feb mandatory pre-shift rapid lateral flow tests for all staff were introduced

Differences in this option

  • Annotation has been taken out of the chart to live in the body text of the page .

Example 2

Publication: Welsh language strategy: annual report 2020 to 2021

Original chart: Chart 3 in the PDF of the report

The original chart is a stacked column chart. Each category in each stack has a data label. The years along the x axis are labelled with diagonal text. A blue colour palette is used. Dark gridlines are used for every 10% on the y axis.

Our version: option a

Figure 2a: Percentage of Year 11 learners in Wales registered for a GCSE in Welsh language, academic year 2008/09 to 2020/21

Large version of a line chart with one line which is a clearer presentation of Year 11 learners in Wales than the original chart.

The line chart shows a gradual increase in the percentage of learners in Wales registered for a GCSE in Welsh language. The percentage stands at 86% in academic year 2020/21, up from 70% in academic year 2008/09.

Source: Welsh Examinations Database (WED) and Pupil Level Annual School Census (PLASC)

Download the data for figure 2a (ODS, 4.4KB).

Summary of edits

  • Changed the chart type from a stacked bar to a line chart.
  • Focused on the increase in the overall percentage of Year 11 learners registered for a Welsh language GCSE
  • Used colours from our colours guidance.

Other things to note:

  • It states that the years are academic years in title.
    • We should always specify the time periods in this way because slashes in years (for example, ‘2008/09’) are not used in a standard way across government.
  • The figures on the y-axis do not have units – this reduces chart clutter.
    • We do not need units after every figure on the y-axis as it states percentages are shown in the title and the y-axis has a percentage symbol at the top.
  • Tick marks have been used on the x-axis to show the data is available for each academic year but only every other year is labelled.
    • This reduces chart clutter, ensures x-axis labels are horizontal and allows a larger font size to be used.
  • The y-axis goes to 100 – this does mean over 8 gridlines are used, but in this example this is OK as we are dealing with percentages.
  • Gridlines are a light grey so they do not distract from the data.
  • Value markers are used on the line – it is OK to use these if you think they help, but they should not be overused.
  • The SVG format has been used for the image of the chart – this means the image retains clarity even when you zoom in.
  • Descriptive alternative text is shown under the chart – this helps people understand what the chart is showing.
  • An accessible data download of the data used in the chart is linked to underneath the chart – this allows people to investigate the data.

Our version: option b

Figure 2b: Percentage of Year 11 learners in Wales registered for a full course GCSE in Welsh language (first and second language), academic year 2008/09 to 2020/21

Large version of a line chart with two lines and an annotation to show detail behind the n the percentage of Year 11 learners registered for a GCSE in Welsh language.

This line chart shows the percentage of Year 11 learners registered for a full course Welsh language GCSE (first language) has increased from 14% to 18% between 2008/09 and 2020/21 (academic years).

It also shows the percentage of Year 11 learners registered for a full course Welsh language GCSE (second language) increased from 26% in 2008/09 to 44% in 2017/18 (academic years). This percentage then rose sharply to 65% in 2018/19 and stands at 68% in 2020/21. The annotation explains that the sharp increase is partly explained by the short course GCSE option being discontinued from September 2018.

Source: Welsh Examinations Database (WED) and Pupil Level Annual School Census (PLASC)

Download the data for figure 2b (ODS 5KB).

Summary of edits

  • This chart shows more detail behind the overall increase in the percentage of Year 11 learners registered for a GCSE in Welsh language.
  • It uses annotation to explain some of the story behind the data.
  • It uses colours from our colours guidance and maintains the rest of the edits discussed in the first option (figure 2a).
  • It is followed by a plain text explanation of the chart (this is the text alternative that gives the equivalent experience of looking at the chart).
  • It also has source information and an accessible data download of the data used in the chart.

Demonstration of making Figure 2b

A video demonstration of making Figure 2b using Excel and PowerPoint will be posted on our Analysis Function YouTube channel soon.

Related links

Support for the presentation, dissemination and communication of data, statistics and analysis. 

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