Co-variation or co-relation between two variables These variables change together Usually scale (interval or ratio) variables
A statistic that quantifies a linear relation between two variables Can be either positive or negative Falls between -1.00 and 1.00 The value of the number (not the sign) indicates the strength of the relation
+.70 or higher Very strong positive relationship +.40 to +.69 Strong positive relationship +.30 to +.39 Moderate positive relationship +.20 to +.29 Weak positive relationship +.01 to +.19 No or negligible relationship -.01 to -.19 No or negligible relationship -.20 to -.29 Weak negative relationship -.30 to -.39 Moderate negative relationship -.40 to -.69 Strong negative relationship -.70 or higher Very strong negative relationship
Something to think about There is a 0.91 correlation between ice cream consumption and drowning deaths. Does eating ice cream cause drowning? Does grief cause us to eat more ice cream?
15 Correlation is NOT causation -e.g., armspan and height