Correlation

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# Correlation - PowerPoint PPT Presentation

Correlation. Topics. Measure of Relationship Strength Direction Scatterplot Conceptual Formula Computational Formula Assumptions Problems Effecting the Interpretation of the Correlation Coefficient. Measure of Relationship.

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## PowerPoint Slideshow about ' Correlation' - kasi

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Presentation Transcript

### Correlation

Topics
• Measure of Relationship
• Strength
• Direction
• Scatterplot
• Conceptual Formula
• Computational Formula
• Assumptions
• Problems Effecting the Interpretation of the Correlation Coefficient
Measure of Relationship
• In a correlational study, two measures -- representing the variables of interest -- are given to onegroup of subjects.
• The subject’s scores on both measures are summarized, and the relationship between the scores on the two measures is examined.
Measure of Relationship
• When the correlation coefficient is used to describe a linear relationship, the coefficient can take on values from -1.00 to +1.00.
• The sign of the correlation indicates the direction of the relationship between two variables.
Measure of Relationship
• A positive relationship means that low scores on X go with low scores on Y whereas high scores on X go with high scores on Y.
• A negative relationship means that as scores on X increase, scores on Y decrease.
• The absolute magnitude or size of the correlation coefficient -- that is, ignoring the plus or minus sign -- indicates the strength of the relationship between X and Y.
Measure of Relationship
• A correlation of +.95 or of -.95 indicates a very strong relationship between the two variables.
• A correlation of 0 indicates that there is no linear relationship between the variables.
• Guilford\'s suggested interpretations for values of r.