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# How to lie with stats and charts. Andrea Maietta, Wide Care Services srl

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# How to lie with stats and charts. Andrea Maietta, Wide Care Services srl

Data Driven Society. May 18th 2018. Data Driven Innovation 2018. Engineering Department, University of Roma Tre

Data Driven Society. May 18th 2018. Data Driven Innovation 2018. Engineering Department, University of Roma Tre

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### How to lie with stats and charts. Andrea Maietta, Wide Care Services srl

1. 1. ANDREA MAIETTA HOW TO LIE WITH STATS AND CHARTS @andreamaietta amaietta@widecareservices.com
2. 2. The truth
3. 3. Alternative truth
4. 4. Is truth either black or white?
6. 6. Statistics are not bad, they’re drawn that way
7. 7. The truth
8. 8. The model
9. 9. Different scale
10. 10. Different precision
11. 11. Different approaches
12. 12. Unwilling lies
13. 13. The truth, the whole truth, and nothing but the truth
14. 14. Lie without lying
15. 15. Lie without lying (sort of)
16. 16. What is the truth? «If you torture data long enough, it will confess to anything» Darrell Huff Thanks to Luca Ruggeri
17. 17. Average
18. 18. Which average?
19. 19. Which average?
20. 20. Which average?
21. 21. Normal distribution
22. 22. Skewed distribution
23. 23. A little example One firm, 90 employees, 3 partners
24. 24. A little example One firm, 90 employees, 3 partners Total wages: \$ 1,980,000
25. 25. A little example One firm, 90 employees, 3 partners Total wages: \$ 1,980,000 Total salaries: \$ 330,000
26. 26. A little example One firm, 90 employees, 3 partners Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000
27. 27. A little example One firm, 90 employees, 3 partners Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000 Average wage: \$ 1,980,000 / 90 = \$ 22,000
28. 28. A little example One firm, 90 employees, 3 partners Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000 Average wage: \$ 1,980,000 / 90 = \$ 22,000 Average salary: (\$ 330,000 + \$450,000) / 3 = \$ 260,000
29. 29. Not impressed
30. 30. Let’s try again Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000
31. 31. Let’s try again Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000 Bonus: \$ 300,000 Profits: \$ 150,000
32. 32. Let’s try again Total wages: \$ 1,980,000 Total salaries: \$ 330,000 Total profits: \$ 450,000 Bonus: \$ 300,000 Profits: \$ 150,000 Total salaries: \$ 330,000 + \$ 300,000 = \$ 630,000
33. 33. Let’s try again Total wages & salaries: \$ 1,980,000 + \$ 630,000 = \$ 2,610,000
34. 34. Let’s try again Total wages & salaries: \$ 1,980,000 + \$ 630,000 = \$ 2,610,000 Average: \$ 2,610,000 / 93 = \$ 28,064
35. 35. Let’s try again Total wages & salaries: \$ 1,980,000 + \$ 630,000 = \$ 2,610,000 Average: \$ 2,610,000 / 93 = \$ 28,064 Profits: \$ 150,000 / 3 = \$ 50,000
36. 36. Let’s try again Total wages & salaries: \$ 1,980,000 + \$ 630,000 = \$ 2,610,000 Average: \$ 2,610,000 / 93 = \$ 28,064 Profits: \$ 150,000 / 3 = \$ 50,000 Profits: 5,7% of total wages & salary
37. 37. That’s better
38. 38. Hiring?
39. 39. Downplay for tax audit?
42. 42. Lie by omission
43. 43. Lie by omission
44. 44. Little omissions
45. 45. Sample size
46. 46. 23% less cavities
47. 47. 9 cats out of 10
48. 48. 90 cats out of 100?
49. 49. Size matters
53. 53. How about this? 90 cats out of 100 in over 1000 experiments 95% confidence interval: 87.3 – 92.7
54. 54. How about this? 90 cats out of 100 in over 1000 experiments 95% confidence interval: 87.3 – 92.7 p = 0.0001
55. 55. 83% of dentists recommend…
56. 56. More than 80% recommend…
57. 57. Wilful misdirection
58. 58. Alcatraz is more expensive than the Waldorf-Astoria
59. 59. It’s safer being in the Navy
60. 60. Y.M.C.A.
61. 61. Percentiles
62. 62. Accidents
63. 63. Accidents
64. 64. Use an index!
65. 65. Spot the difference
66. 66. Average houses for average people
67. 67. Average people Average family: 3.6 persons
68. 68. Average people Average family: 3.6 persons (count as 4)
69. 69. Average people Average family: 3.6 persons (count as 4) two bedrooms
70. 70. Average people (detail) 3 or 4 persons (two bedrooms): 45%
71. 71. Average people (detail) 3 or 4 persons (two bedrooms): 45% 1 or 2 persons (one bedroom): 35%
72. 72. Average people (detail) 3 or 4 persons (two bedrooms): 45% 1 or 2 persons (one bedroom): 35% More than 4 (three bedrooms): 20%
73. 73. Average people (detail) 3 or 4 persons (two bedrooms): 45% 1 or 2 persons (one bedroom): 35% More than 4 (three bedrooms): 20% Won’t buy: 55%
75. 75. Deviations
76. 76. Deviations
77. 77. What is a difference?
78. 78. What is a difference?
79. 79. Charts
80. 80. Don’t extrapolate
81. 81. Sub-10sec World Record 100m Times (Men)
82. 82. Times change, people change, hairstyles change
83. 83. The past is in the past
85. 85. Omit selection
86. 86. Truncate the y-axis
87. 87. Remove labels
88. 88. Shrink the x-axis
89. 89. Decreasing sales
90. 90. Cumulative sales
91. 91. Global warming
92. 92. Absolute temperatures (complete set)
93. 93. Temperature change
94. 94. Cherry picking
95. 95. 3D Charts
96. 96. R&D Research 55%
97. 97. R&D Research 55% Grant 18%
98. 98. R&D Research 55% Grant 18% Admin 27%
99. 99. Does it ring a bell?
100. 100. Let’s graph it 0% 10% 20% 30% 40% 50% 60% Admin Grant Research
101. 101. Turn it into a 3D chart 0% 10% 20% 30% 40% 50% 60% Admin Grant Research
102. 102. Alter perspective 0% 10% 20% 30% 40% 50% 60%
103. 103. Change chart type 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Research Grant Admin
104. 104. Alter shape 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 Research Grant Admin
105. 105. Pie charts
106. 106. Pie chart Research Grant Admin
107. 107. A bit of perspective Research Grant Admin
108. 108. It works miracles!
109. 109. Pictocharts
110. 110. Heights or areas?
111. 111. Correlation or causation?
112. 112. IE users are killers
113. 113. Pirates cause global warming
114. 114. Recap
115. 115. Everybody lies
116. 116. Number and percentages sound closer to the truth
117. 117. We feel deference for authorities
118. 118. We trust uniforms
119. 119. Even when they’re not (and we know it)
120. 120. Milgram, 1974
121. 121. Dangerous combination
122. 122. Be careful
123. 123. Constant vigilance!
124. 124. “the only thing that anybody with brains should be doing with their life”
125. 125. Q&A