Lab9_corr - Lab 9 Correlation& Regression Learning...

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Unformatted text preview: Lab 9 Correlation & Regression Learning Objectives Compute correlations and regression lines by hand and by SPSS. Understand the meaning and uses of correlation & regression. Understand the limits of study designs in which the IV is not manipulated. Part 1: Correlation Describing the correlation Long name: Pearson product-moment correlation coefficient. Aka “Pearson’s r” aka “correlation coefficient.” Notation. Numerical summary of joint distribution labeled r in the sample and rho • ( ) in the population. Single number that summarizes a scatterplot. Purpose – tells the form and magnitude of relations between 2 variables. ρ Properties of r The range of r is form –1 thru 0 to +1. The sign of r tells the direction of relations between the 2 vbls. The magnitude of r tells how closely the 2 vbls are related. See handout 1. Positive Correlations 30 20 10 Hours Studied 100 90 80 70 60 Grades Positive Correlation 30 27 24 21 18 15 Hours Studied 100 90 80 70 60 Grades Positive Correlation r = 1 As study time increases, test scores improve. If we had a perfect relationship between study time and test scores, we would see r = 1 (right graph)....
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Lab9_corr - Lab 9 Correlation& Regression Learning...

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