Data Literacy

A number without context has no meaning. Likewise, a story with no evidence to support it may be difficult to believe. Data and narrative naturally work hand-in-hand to communicate meaning to an audience. Both tables and visualizations can be used to present data, either on their own or as part of a narrative. Data should be integrated with the story and not distract - too much data, or poorly presented data, may confuse the audience and make them disinterested in the message.

Consider your story: what is the message you're trying to communicate? What have you found or accomplished?

Consider your data: what sort of data do you have? What are the most compelling findings? Can you string these findings together to help tell a story?

Also consider your audience: who are you hoping will read/hear your presentation? What ways of communicating data are they familiar with?

These concepts are often discussed as "storytelling with data", and many articles, books, and courses have been written on the topic. Some of them can be found linked at the bottom of this page.

#1: Always use a number if you can.

• Numbers help with precision.

#2: Never use a number if you don’t know where it’s been.

• Any number depends on a clear definition of what is measured and how.
• Numbers are more robust if they are based on definitions and measurements that are widely agreed and whose strengths and weaknesses are well understood.

#3: Comparisons need care.

• Compare like with like.
• Comparisons over time or across different groups can only be made if the measurement method stays the same.
• Definitions used by different organizations or countries or in different time periods rarely coincide exactly.

#4: Embrace uncertainty.

• Often, it is sensible to report a range within which the true value of a measurement is thought to lie. 
• However, number ranges that do not have both upper and lower limits are meaningless.

#5: Orders of magnitude matter.

• Numbers should be presented with some readily recognizable comparisons that make their magnitude comprehensible. 
• There are three questions that you should work through to ensure that your numbers make their magnitude comprehensible:
• Do they make substantive sense?
• Are they consistent?
• Are the numbers meaningful to a reader? 

#6: (At least) two is company.

• A number presented on its own may be there just to give a spurious air of scientific credibility to an argument. 
• Usually we need to make comparisons between numbers to make sense of what is going on. 

#7: Three is plenty.

• Readers may switch off if you use too many numbers.
• Remedies to avoid reader switch-off:
• Round numbers to 3 significant digits or fewer to avoid long lists of figures.
• Use a picture (like a chart!) to tell a story.