Numbers that lie: Understanding and presenting data

I've seen things you people wouldn't believe - pie charts about response times, line charts without axis descriptions... My fear is all those things won't fade in time, like tears in the rain.
Working in a software company means processing tons of data. You don't have to be a data scientist to be asked to aggregate it and present it to someone; even worse - be on the receiving end of poorly prepared data. But it doesn't have to be that way. I'd like to show some examples, tips, and tricks to help you read and present data better. You're welcome :)

Transcript

1. Numbers that lie Understanding and presenting data Piotr Czajka 2024
5. • Data presentation fails • Case study of a chart • Case study of a visualization • A few tips on doing visualization well • Q&A
7. Let’s … go
10. I’ve seen things you people wouldn’t believe
11. Dishonest
16. Too fancy
22. Visualization as riddle
29. Didn’t think this through
35. Too much
40. Pies we love
42. Pies we hate
44. Comparing pie charts Market share in the UK A B C D E Market share in the USA A B C D E
45. 0 20 40 60 80 100 120 A Market share in the UK A B C D E 0 20 40 60 80 100 120 A Market share in the USA A B C D E
46. 0 5 10 15 20 25 30 35 40 45 A B C D E Market share in the UK vs. USA UK USA
47. Sales Lager Lambic IPA APA Porter Witbier
48. Sales Lager Lambic IPA APA Porter Witbier
49. Sales Lager Lambic IPA APA Porter Witbier
50. Sales Lager Lambic Porter Witbier IPA APA
51. 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 Lager Lambic Porter Witbier IPA APA Sales Lager Lambic Porter Witbier IPA APA
52. Should I stop using pie charts, then?
54. Reasons you might choose pie charts
55. When there is only one slice of the pie, it’s easier to show its’ share of the whole value Favourite Muppets character Kermit the Frog Other
56. You have a square (not rectangular) space for visualization How much this is A half A quarter A piece of eight A piece of eight 0 10 20 30 40 50 60 A half A quarter A piece of eight A piece of eight How much this is A half A quarter A piece of eight A piece of eight
57. It’s too complicated to display the information as a bar graph How much this is A half A quarter A piece of eight A piece of eight 0 10 20 30 40 50 60 A half A quarter A piece of eight A piece of eight How much this is A half A quarter A piece of eight A piece of eight
58. Users are used to this chart from past visualizations
59. Data is in %, and only two values are displayed 43% 57% Favourite Muppets character Kermit the Frog Other
60. Non-graph visualization
62. 743mln 1200mln 457mln
63. 743mln 1200mln 457mln 457mln 457mln 457mln 457mln
64. 743mln 1200mln 457mln
65. 0 200 400 600 800 1000 1200 1400 Why we must rise garbage fees Citizens play Payed from city budget
66. 0 200 400 600 800 1000 1200 1400 Why we must rise garbage fees Citizens play Payed from city budget
67. Good data presentation
68. Remember you can’t satisfy all audiences
69. Understand the context • Who is your audience? • What information you want to pass to them?
70. Select a fitting graph What type of graph will convey your message the best?
71. Show one big number
72. Compare values
73. Composition
74. Change over time
75. Relations
76. Remove distractors • How much data is enough? • Selecting colours and using empty space. DISTRACTION YET ANOTHER MEANINGLESS MESSAGE TO KEEP YOU FROM PAYING ATTENTION TO ALL OF THE ISSUES THAT REALLY MATTERS DISTRACTION YET ANOTHER MEANINGLESS MESSAGE TO KEEP YOU FROM PAYING ATTENTION TO ALL OF THE ISSUES THAT REALLY MATTERS DISTRACTION YET ANOTHER MEANINGLESS MESSAGE TO KEEP YOU FROM PAYING ATTENTION TO ALL OF THE ISSUES THAT REALLY MATTERS DISTRACTION YET ANOTHER MEANINGLESS MESSAGE TO KEEP YOU FROM PAYING ATTENTION TO ALL OF THE ISSUES THAT REALLY MATTERS DISTRACTION YET ANOTHER MEANINGLESS MESSAGE TO KEEP YOU FROM PAYING ATTENTION TO ALL OF THE ISSUES THAT REALLY MATTERS
77. Guide the attention • How people will read your graph? • How to highlight important information. • Think like a designer – less is more.
78. Tell a story That’s a topic for another time ;)
79. Numbers don’t lie
80. People do
81. Don’t be one of them
84. Bibliography • Nussbaumer Knafic, Cole. 2015. Storytelling with Data: A Data Visualization Guide for Business Professionals. Wiley. • Barker, Hugh. 2022. Lying Numbers: How Maths and Statistics Are Twisted and Abused. Robinson. • Bąk, Janina. 2022. Statystycznie rzecz biorąc. WAB. • https://jezykdanych.pl • https://scc.ms.unimelb.edu.au/resources/data-visualisation-and- exploration/no_pie-charts