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Understanding Data
1. Not Waving But Drowning Understanding Data Andrew Hingston switchsolutions.com.au
2. Not Waving But Drowning by Stevie Smith Nobody heard him, the dead man, But still he lay moaning: I was much further out than you thought And not waving but drowning. Poor chap, he always loved larking And now he's dead It must have been too cold for him his heart gave way, They said. Oh, no nono, it was too cold always (Still the dead one lay moaning) I was much too far out all my life And not waving but drowning. Name and what you do Hobby others don’t know Waving or drowning in data?
7. Sources of POWER Legitimate power Referent power Expert power Reward power Coercive power French and Raven (1959)“The bases of social power”See Wikipedia:“Power (philosophy)” 7
8. Persuasion Reciprocity Consistency Social proof Authority Liking Scarcity Robert Cialdini (2001)“Influence: Science and practice”See Wikipedia “Robert Cialdini” 8
13. Why visualise your data? For you Fast understanding Build solid ‘foundation’ Flags problems 13 For others Easier to follow Memorable Less info overload More convincing
40. BOX PLOTS Mean and median Spread Symmetry Outliers 40 BAD GOOD Not intuitive Need stats package Bad for presentations
41. Interpreting shape 41 Right-Skewed Left-Skewed Symmetric Q Median Q Q Median Q Q Median Q 1 3 1 3 1 3 * * * Mean
42. Side-by-side boxplots If boxes don’t overlap then difference between groups is ‘statistically significant’ BUT THIS IS A PRETTY ROUGH TEST! 42 Boxes DON’T overlap
46. 46 NORMALdistribution 68.2% chance 95.4% chance 99.7% chance stddev stddev Bell shaped mean=median=mode symmetricalGoes from - to + Area under curve = 1
50. Calculating probability 50 stddev =1 mean = 0 X = How many stddev from the mean? This is called Z Put Z into spreadsheet = NORMSDIST ( 1 ) which gives 84% P.S. is mean is stddev
51. … is the same as … 51 stddev =1 mean = 2 X = How many stddev from the mean? This is called Z Put Z into spreadsheet = NORMSDIST ( 1 ) which gives 84% P.S. is mean is stddev
52. … or take a shortcut! 52 stddev =1 mean = 2 X = In OpenOfficeCalc = NORMSDIST ( 1 ) which gives 84% = NORMDIST ( 3 ; 2 ; 1; 1 ) also gives 84% P.S. is mean is stddev X
56. Double - Peaked Bell - Shaped Comb Plateau Skewed Truncated Edge - Peaked Isolated - Peaked But data might not be Normal 56
57. Central Limit Theorem The shape of the data doesn’t matter … if you take a large enough sample ( > 30 ) the means of the sample will follow a Normal distribution shape around the mean of the underlying data 57 DEMO
58. Use modified Z-score formula for probabilitythat mean of a sampletakes on certain values 58 is mean is stddevn is sample size Use Z-score formulaif your data follows aNormal distribution
61. Exercises in R Test Data Exercise 4 Employee Expenses Exercise 5 Toll Booth Exercise 6 Cycle World Exercise 9 Chan’s Linen Exercise 10 Stock returns For the brave! Exercise 11 Social Insight Test Exercise 13 Quality Exercise 16 Car production 61