Definition
Correlation
The direction and strength of a linear relationship between two numerical variables.
Continue from this idea into connected AXIO math.
Up together is positive; opposite directions are negative.
Boundary: Correlation describes a linear pattern. Two variables can have a strong curved association but a weak linear correlation.
What it means
If points in a scatter plot gather around an upward line, the correlation is positive. Around a downward line, it is negative. The closer the points follow a line, the stronger the correlation.
Remember it
Up together is positive; opposite directions are negative.
Example
A scatter plot of outdoor temperature and ice-cream sales forms a tight upward pattern. The variables have a strong positive correlation: warmer days tend to come with higher sales.
Watch for
Correlation describes a linear pattern. Two variables can have a strong curved association but a weak linear correlation.
Common mix-up
Strong correlation does not prove that one variable caused the other.
Exact meaning
Correlation describes the direction and strength of a linear relationship between two numerical variables. A correlation coefficient can summarize it with a value from −1 to 1.