7. 3.3 Cautions

8. Correlation and Regression Wisdom
Correlation and regression describe ONLY LINEAR relationships
Extrapolations (using data to predict outside the range of the data) can produce unreliable results
Correlation is not resistant

9. Correlation and Regression Wisdom
Correlation based on averages is usually too high to apply to individuals
Outlier is an observation that lies outside the overall pattern of the other observations
An observation is influential for a statistical calculation if removing it would markedly change the result of the calculation

10. Correlation and Regression Wisdom
lurking variables—variable that is not the explanatory and/or response that may influence the interpretation of the relationships
“Math is gatekeeper for success in college”
Family background is lurking variable

11. Correlation and Regression Wisdom
Correlation does not imply causation!!
Year
# Of Ministers in New England
Cuban Rum Imported
1860 63
8376
1865 48
6406
1870 53
7005
1875 64
8486
1880 72
9595
1885 80
10,643
1890 85
11,265
1895 76
10,071
1900
10,547
1905 83
11,007

12. HW: pg 242 #63-64, 67, 70