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Unformatted text preview: Inferential Statistics Chapter 14 & 15 Overview Finish Chp 14 Correlations Chp 15 Symbols & Terms Hypothesis Testing Sampling Distributions Estimation Inferential Statistics Test hypotheses Correlations: Relationship between IV and DV 2 Interval or Ratio variables TTests: Differences between 2 groups Nominal IV, Interval or Ratio DV Review: Correlations Correlation &#224; when two variables change together Correlation Coefficient ( r ) : number indicating the strength and direction a linear relationship between two variables. Both variables need to have interval or ratio level data. Exercise Health Problems Calculating Correlations Suppose you collected data on IQ and the number of episodes of Jersey Shore that people watched. Here are the relevant data Name IQ Hours watching JS Kristin 119 2 Darrell 124 2 Privia 90 14 Eileen 110 10 Connor 111 5 Jamal 110 7 Crystal 114 6 Natalie 127 Deepa 105 11 Melinda 100 13 (z xz y) N r = Plan of attack: Calculating Correlations 1. Calculate Mean and Standard Deviation for each variable 2. Calculate each persons Zscore for variables x and y 3. Multiply each persons Zscores together 4. Add the Zscore products together 5. Divide by number of subjects Descriptives Step 1: Calculate Mean and Standard Deviation for variables IQ : Mean=111, s=10.48 Hours : Mean=7, s=4.63 Calculating Correlations Name IQ Hours watching Jersey Shore Kristin 120 2 Darrell 124 2 Privia 90 14 Eileen 110 10 Connor 111 5 Jamal 110 7 Crystal 114 6 Natalie 127 Jana 105 11 Deepa 100 13 .86 1.242.00.10.10 .29 1.53.571.051.081.08 1.51 .65.43.221.51 .86 1.30 z for IQ z for Jersey Shore Step 2: Calculate each persons Zscores for variables IQ and hours _ X X SD Z = IQ Mean=111, s=10.48 Hours Mean=7, s=4.63 Calculating Correlations Name IQ Hours watching Jersey Shore z for IQ Z for JS Kristin 120 2 .861.08 Darrell 124 2 1.241.08 Privia 90 142.00 1.51 Eileen 110 10.10 .65 Connor 111 5.43 Jamal 110 7.10 Crystal 114 6 .29.22 Natalie 127 1.531.51 Deepa 105 11.57 .86 Melinda 100 131.05 1.30 z(IQ)*z(JS).931.343.02.07.062.31.491.37 Step 3: Multiply each persons Zscores together Step 4: Add the Zscore products together (the z(IQ) * z(JS) column). Finally Step 4: Add the Zscore products together (the z(IQ) * z(JS) column). Step 5: divide by the number of subjects....
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This note was uploaded on 02/27/2012 for the course HERE 2345 taught by Professor Mikerotch during the Fall '11 term at MO St. Louis.
 Fall '11
 MikeRotch

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