Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187)...
-
Upload
clara-harper -
Category
Documents
-
view
225 -
download
0
Transcript of Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187)...
![Page 1: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/1.jpg)
Correlations
11/7/2013
![Page 2: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/2.jpg)
Readings
• Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187)
• Chapter 8 Correlation and Regression (Pollock Workbook)
![Page 3: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/3.jpg)
Homework Due Today
• Chapter 7 Pollock Workbook – Question 1 • A, B, C, D, E, F
– Question 2 • A, B, C, D
– Question 3 (use the dataset from the homework page)• A, B, C, D
– Question 5 • A, B, C D, E
![Page 4: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/4.jpg)
OPPORTUNITIES TO DISCUSS COURSE CONTENT
![Page 5: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/5.jpg)
Office Hours For the Week
• When– Friday 10-12– Monday 10-12– Tuesday 8-12– And by appointment
![Page 6: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/6.jpg)
Course Learning Objectives
1. Students will be able to interpret and explain empirical data.
2. Students will achieve competency in conducting statistical data analysis using the SPSS software program.
![Page 7: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/7.jpg)
Correlations
![Page 8: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/8.jpg)
What is correlation?
• Any relationship between two variables
• Correlation does not mean causation
![Page 9: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/9.jpg)
What Could Be Happening?
• Variable A influences variable B
• Variable B influences variable A
• It is a coincidence
• Some other variable (C) influences both A and B
![Page 10: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/10.jpg)
Measuring Pearson’s r
• Measure from -1 to 0 to 1. – -1 means a perfect
negative relationship – 0 is the absence of any
relationship – +1 is a perfect positive
relationship
• Like Somers’ D, Pearson's "r" scores tell us – Direction – Strength of Association – Statistical significance of
the measure
![Page 11: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/11.jpg)
PEARSON'S r's are PRE Measures!
• Squaring the (r) value provides a measure of how much better we can do in predicting the value of the d.v by knowing the independent variable.
• We call this a r2 (r-square) value.
![Page 12: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/12.jpg)
SCATTERPLOTS
![Page 13: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/13.jpg)
A Way of Visualizing a Correlation
![Page 14: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/14.jpg)
More on Scatterplots• We can think of this line as a
prediction line.
• The closer the dots to the line, the stronger the relationship, the further the dots the weaker the line.
• If all the data points are right on the regression line, then there is a perfect linear relationship between the two variables.
• This only graphs a correlation...... this means that it does not mean causality nor should it be used for testing!
![Page 15: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/15.jpg)
CO2 and Urban Population
![Page 16: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/16.jpg)
SCATTERPLOTS IN SPSS
![Page 17: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/17.jpg)
How to do it
• Graphs • Legacy Dialogs • Scatter/Dot...
![Page 18: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/18.jpg)
A Window pops upSelect simple
Choose Define
![Page 19: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/19.jpg)
Adding Case Labels
• put your variable in the Label Cases by area
• Click on Options, and this will open up a window – Click on display chart
with case labels and continue • Click OK
![Page 20: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/20.jpg)
Including a fit Line with your Scatterplot
![Page 21: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/21.jpg)
![Page 22: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/22.jpg)
Do not use scatterplots for testing! There are better measures, especially if you have more than 1 iv. (your paper should not include any scatterplots)
![Page 23: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/23.jpg)
Lets try an example
• Use the following data set
• D.V. Obama• I.V. Unemp
• Follow the directions from last class
![Page 24: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/24.jpg)
What is Going on?• The Line of Best Fit-
• How much error is in our line.
• A predictor for future values • Eyeballing the data, a state with
4% unemployment should give Obama how much support?
![Page 25: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/25.jpg)
DATA
![Page 26: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/26.jpg)
Primary data
• Collection
• Advantages
• Disadvantages
![Page 27: Correlations 11/7/2013. Readings Chapter 8 Correlation and Linear Regression (Pollock) (pp. 182-187) Chapter 8 Correlation and Regression (Pollock Workbook)](https://reader036.fdocuments.in/reader036/viewer/2022062321/56649e025503460f94aec1ab/html5/thumbnails/27.jpg)
Secondary Data
• Collection
• Advantages
• Disadvantages