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Scientific Inquiry SCI 105.020 Correlation Vs. Causation.

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Presentation on theme: "Scientific Inquiry SCI 105.020 Correlation Vs. Causation."— Presentation transcript:

1 Scientific Inquiry SCI 105.020 Correlation Vs. Causation

2 Correlation Correlation is a relationship between two variables, each with various numbers of possible values. Variables Color Size Values Red, Green Large, Small

3 Correlated or Not Not correlated Correlated Small Large Red Green Small Large Red Green

4 Causation Correlation is a necessary condition for a causal relationship, but not a sufficient one Examples  Using ashtray & suffering lung cancer  Red spots, fever and measles C Cause Not C E Effect Not E

5 Causation Is Not Symmetric Correlation is symmetric  Being small is negatively correlated with being red.  Being red is also negatively correlated with being small. Causation is not  Smoking causes cancer  Suffering cancer causes smoking (???) Small Large Red Green CE

6 Find out the Hidden Variable In many situations, two correlated variables are not linked with a casual relationship directly. But there is a hidden variable that determines the association.  Using ashtray   lung cancer  Hidden variablesmoking

7 Sample Data Day MinutesDay CallsDay Charge 265.111045.07 161.612327.47 243.411441.38 299.47150.9 166.711328.34 223.49837.98 218.28837.09 1577926.69 184.59731.37 258.68443.96 129.113721.95 187.712731.91 128.89621.9 156.68826.62 120.77020.52 332.96756.59 196.413933.39 190.711432.42

8 Scatter Plot – No-Association

9 Scatter Plot - Strong Association

10 Scatter Plot – Linear-Linear

11 Scatter Plot – Linear-Logarithmic


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