Language for describing correlations

• Do the data points have a pattern that suggests there is correlation?

• Can a line of best fit be drawn to show the relationship?

• If there is a correlation, what is the direction of the correlation?

• What is the strength of the correlation?

Graph A: X & Y are not correlated.

Graphs B through E:X and Y are correlated

or X and Y are related,X and Y are associated

Do the data points have a pattern that suggests there is

correlation?

Diagram: education.com

Can a line of best fit be drawn to show the relationship?

Graphs B – E show a dotted line, which is a line of best fit.

Draw the line where it is the closest to all of the points, cutting through the middle of the data cloud.

The line of best fit might be helpful when thinking about both the direction and strength.

Note that it does not connect the points!

If Y increases when X increases, it is a positive correlation (Graph B and C).

If Y decreases when X increases, it is a negative correlation (Graph D and E).

If there is a correlation, what is the

direction of the correlation?

The strength of the relationship has to do with variability.

If the data are spread out, even though you can see a general pattern, then the correlation is weak (Graph B & D)

If the data are really tight along an imaginary line that shows the pattern, then the correlation is strong. Graphs C and E.

What is the strength of the correlation?