A graph used to display the relationship between two quantitative variables measured on the same individuals.
A way of describing a scatterplot relationship.
How closely the points fit the "form"; weak, strong.
High values of one variable tend to occur together with high values of the other variable.
High values of one variable tend to occur together with low values of the other variable.
Not on the general line "drawn" for the scatterplot; if on the line, not actually an outlier.
Correlation Coefficient (definition)
A measure of the direction and strength of a relationship; calculated using the mean and standard deviation of both the X and Y variables. Given as "r".
Correlation Coefficient (equation)
r = (1 / n-1) ∑ (x₋i - x₋bar/ s₋x)(y₋i - y₋bar/ s₋y)
x₋bar = mean for the dependent variable
y₋bar = mean for the independent variable
s₋x = standard deviation for the dependent variable
s₋y = standard deviation for the independent variable
Correlation makes no distinction between explanatory and response variables.
It doesn't matter what's called what in calculating the correlation.
r does not change when we change the units of measurement of x, y, or both
In calculating correlation, elements are standardized; standardizing eliminates units.
The correlation r is always a number between -1 and 1.
Negative indicates negative correlation, positive indicates positive; zero indicates no correlation.