This document summarizes three common errors in statistical thinking: 1) Misleading bar charts that can compare "apples to oranges" rather than "apples to apples". 2) Mistaking correlation for causation, when correlation only shows a relationship between variables but does not prove one causes the other. 3) Confusing statistical significance with practical significance, where a statistically significant finding may not necessarily be meaningful or substantial.

1. 3Three Common Errorsin statistical thinking

2. OverviewMisleading bar chartsCorrelation and causationTwo kinds of significance

3. Error1Misleading Bar Charts

4. Student Satisfaction Data Excerpt?Can you compare “apples to apples” using this chart?

5. Student Satisfaction Data Excerpt?Can you compare “apples to oranges” using this chart?Can you compare “apples to apples” using this chart?

6. Student Satisfaction Data Excerpt

7. Error2Correlation & Causation

8. VariablesAn aspect of someone or something that is free to vary – that is, different values are possible

9. CorrelationHow 2 variables change (vary) in relationship

10. CORRELATION

11. Correlations of ±1.00

12. An Interesting CorrelationSources: FBI Crime Statistics (http://www.fbi.gov/ucr/cius_04/documents/CIUS_2004_Section2.pdf) and USDA Dairy Statistics (http://usda.mannlib.cornell.edu/usda/nass/DairProd//2000s/2005/DairProd-02-04-2005.pdf)

13. Interesting Causation…?Landers, J.B. (n.d.). On CAUSEweb.org. Retrieved from http://www.causeweb.org/

14. CausationCausation has at least 3 requirementsCorrelationTemporal precedenceControl (elimination) of other possible causes

15. Error3Two kinds of significance

16. Statistical SignificanceNull hypothesis significance testing?H0

17. Practical SignificanceWhat do you mean by “significant”?