Correlation

Error and Uncertainty in Google Sheets

Evan Kramer

Instructor

Correlation

• Relationship between two groups
• Correlation coefficient (r)
  • Varies between -1 and 1
    • Positive: Increase/decrease together
    • Negative: Opposite increases/decreases
    • Zero: No relationship

The CORREL() function

• CORREL() function
  • Two numeric data ranges
• Correlate values in columns G and H
  • =CORREL(G:G,H:H)

Evaluating strength of relationships

• Weak
  • -0.3 to 0.3
• Moderate
  • -0.3 to -0.7 or 0.3 to 0.7
• Strong
  • -0.7 to -1.0 or 0.7 to 1.0

Problems with correlation

• Example
  • Ice cream consumption and drowning deaths
• Causation
  • A causes B?
  • B causes A?
• Third variable problem
  • C causes both A and B?

Let's practice!

Error and Uncertainty in Google Sheets