co-variation or co-relation between two variables these variables change together usually scale...
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Co-variation or co-relation between two variables
These variables change togetherUsually scale (interval or ratio)
variables
A statistic that quantifies a linear relation between two variables
Can be either positive or negativeFalls between -1.00 and 1.00The value of the number (not the
sign) indicates the strength of the relation
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Linear relationships Curvilinear relationships
Slide from: Statistics for Managers Using Microsoft® Excel 4th Edition, 2004 Prentice-Hall
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Strong relationships Weak relationships
Slide from: Statistics for Managers Using Microsoft® Excel 4th Edition, 2004 Prentice-Hall
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No relationship
Slide from: Statistics for Managers Using Microsoft® Excel 4th Edition, 2004 Prentice-Hall
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Association between variables such that if one variable increases, then the other increases.A direct relation between the variables
Association between variables such that if one variable increases, then the other decreasesAn inverse relation between the
variables
+.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?
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Correlation is NOT causation
-e.g., armspan and height
Correlation is not causation. Invisible third variables
Three Possible Causal Explanations for a Correlation
Correlation coefficient quantifies the linear relationship of two variables
Also called “r” or “r factor”Shows how strongly they are
connectedNot proof of causality (causation)