Lecture_2 - Association: Contingency, Correlation, and...

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Unformatted text preview: Association: Contingency, Correlation, and Regression How Can We Explore the Association between Two Categorical Variables? Learning Objectives 1. Identify variable type: Response or Explanatory 2. Define Association 3. Contingency tables 4. Calculate proportions and conditional proportions Learning Objective 1: Response and Explanatory variables Response variable (Dependent Variable) the outcome variable on which comparisons are made Explanatory variable (Independent variable) defines the groups to be compared with respect to values on the response variable Example: Response/Explanatory Blood alcohol level/# of beers consumed Grade on test/Amount of study time Yield of corn per bushel/Amount of rainfall Explanatory (independent) variable: number of beers Response (dependent) variable: blood alcohol content x y Explanatory and response variables A response variable measures or records an outcome of a study. An explanatory variable explains changes in the response variable. Typically, the explanatory or independent variable is plotted on the x axis and the response or dependent variable is plotted on the y axis. Learning Objective 2: Association The main purpose of data analysis with two variables is to investigate whether there is an association and to describe that association An association exists between two variables if a particular value for one variable is more likely to occur with certain values of the other variable Association: Contingency, Correlation, and Regression How Can We Explore the Association between Two Quantitative Variables? Learning Objectives: 1. Constructing scatterplots 2. Interpreting a scatterplot 3. Correlation 4. Calculating correlation Learning Objective 1: Scatterplot Graphical display of relationship between two quantitative variables: Horizontal Axis: Explanatory variable , x Vertical Axis: Response variable , y Learning Objective 1: Internet Usage and Gross National Product (GDP) Data Set INTERNET GDP INTERNET GDP Algeria 0.65 6.09 Japan 38.42 25.13 Argentina 10.08 11.32 Malaysia 27.31 8.75 Australia 37.14 25.37 Mexico 3.62 8.43 Austria 38.7 26.73 Netherlands 49.05 27.19 Belgium 31.04 25.52 New Zealand 46.12 19.16 Brazil 4.66 7.36 Nigeria 0.1 0.85 Canada 46.66 27.13 Norway 46.38 29.62 Chile 20.14 9.19 Pakistan 0.34 1.89 China 2.57 4.02 Philippines 2.56 3.84 Denmark 42.95 29 Russia 2.93 7.1 Egypt 0.93 3.52 Saudi Arabia 1.34 13.33 Finland 43.03 24.43 South Africa 6.49 11.29 France 26.38 23.99 Spain 18.27 20.15 Germany 37.36 25.35 Sweden 51.63 24.18 Greece 13.21 17.44 Switzerland 30.7 28.1 India 0.68 2.84 Turkey 6.04 5.89 Iran 1.56 6 United Kingdom 32.96 24.16 Ireland 23.31 32.41 United States 50.15 34.32 Israel 27.66 19.79 Vietnam 1.24 2.07 Yemen 0.09 0.79 Enter values of explanatory variable (x) in L1 Enter values of of response variable (y) in L2 STAT PLOT Plot 1 on Type: scatter plot X list: L2 Y list: L1 ZOOM 9:ZoomStat Graph Learning Objective 1: Internet Usage and Gross National Product (GDP) Learning Objective 1: Baseball Average and Team Scoring...
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This note was uploaded on 05/25/2011 for the course STA 2023 taught by Professor Frade during the Spring '11 term at Florida A&M.

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Lecture_2 - Association: Contingency, Correlation, and...

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