Lecture 4 - Relationships between variables Bivariate Data...

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Relationships between variables Bivariate Data consists of the values of two different response variables that are obtained from the same population element. Example: A physical therapist measures the grip strength and overall arm strength of patients recovering from an arm injury. Scatter Diagram – A plot of all the ordered pairs of bivariate data. The scatter diagram will show the nature of the relationship between the two variables.
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Linear Correlation Linear correlation analysis looks at the strength of a linear relationship between 2 variables. Properties of the Linear Correlation Coefficient 1. The sample linear correlation coefficient is denoted ‘ r ’. 2. The correlation coefficient is between negative one and one. –1 ≤ r ≤ +1. 3. r > 0 indicates a positive linear relationship r < 0 indicates a negative linear relationship r = 0 indicates no linear relationship
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Computing Pearson's correlation coefficient ) ( ) ( ) ( y SS x SS xy SS r = ( 29 n x x
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This note was uploaded on 02/15/2009 for the course STAT 2004 taught by Professor Melutz during the Fall '07 term at Virginia Tech.

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Lecture 4 - Relationships between variables Bivariate Data...

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