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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

  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?
  5. 5. Shades of grey
  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?
  40. 40. Heads or tails?
  41. 41. Heads or tails?
  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
  50. 50. The missing link
  51. 51. How about this? 90 cats out of 100
  52. 52. How about this? 90 cats out of 100 in over 1000 experiments
  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%
  74. 74. Bad mistake
  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
  84. 84. Bad sales
  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
  126. 126. Readings
  127. 127. How to lie with statistics
  128. 128. Truth, lies and statistics
  129. 129. Graphs don’t lie
  130. 130. ANDREA MAIETTA HOW TO LIE WITH STATS AND CHARTS @andreamaietta amaietta@widecareservices.com

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