Three Types of Correlation

Correlations come in three flavors.

  1. Positive correlation. Example: temperature with ice cream sales. As temperature goes up, on average ice cream sales go up.
  2. Negative correlation. Example: hours spent watching TV with grades in class. The more hours a student spends watching TV per week, typically the lower his/her Grade Point Average (GPA).
  3. Zero correlation. Example: number of letters in the name of a city with longitude. Cities with long names are just as likely to be located North as South.