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# presentation 5 - Chapter 5: Correlation Correlation:...

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Chapter 5: Correlati on

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When trying to find the relationship between two different variables, we usually need to standardize the variables so that they can be compared. To do this, we transform raw scores of each variable into Z scores , or the number of standard deviation a particular score is from the mean. Correlation: Assessing association between Variables
Z = X-μ/σ μ and σ are the mean and standard deviation respectively. Z score indicate whether it is above or below the mean, whereas the magnitude of a z score indicates how far it is above or below the mean. Z score

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Correlation Coefficient:  To quantify a correlation,  we calculate the correlation coefficient, which is a  statistic that quantifies a relation between two  variables. Positive or negative Between -1 and 1 Strength of the coefficient indicates how large it is
What is difference between a positive and  negative correlation? Positive Correlation:  Negative Correlation:

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Which is strong? +0.2 or -0.7
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## This note was uploaded on 02/21/2012 for the course PYSC 227 taught by Professor Fairchild during the Fall '10 term at South Carolina.

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presentation 5 - Chapter 5: Correlation Correlation:...

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