Measuring Correlation (Leaving Cert Mathematics): Flashcards

Strength & direction of relationship between 2 variables

$r$

Between $-1$ and $+1$

$r = 1$

$r = -1$

$r = 0$

All points lie exactly on an upward straight line

All points lie exactly on a downward straight line

Positive correlation

Negative correlation

How close $r$ is to $1$ or $-1$

No linear relationship (not no relationship at all)

How close points are to a straight line

Both variables increase together

One variable decreases as other increases