Chapter 13 A - Chapter 13 Correlation and Regression...

Info iconThis preview shows pages 1–16. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 13 Correlation and Regression
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
General Examples Does a change in one variable significantly affect another variable? Do two scores tend to co-vary positively (high on one score high on the other, low on one, low on the other)? Do two scores tend to co-vary negatively (high on one score low on the other; low on one, hi on the other)? Interval Nominal Dependent Variable Independent Variables Nominal Interval
Background image of page 2
Specific Examples Does getting older significantly influence a person’s political views? Does marital satisfaction increase with length of marriage? How does an additional year of education affect one’s earnings? Interval Nominal Dependent Variable Independent Variables Nominal Interval
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Why use correlation and regression analysis? To determine if there is a relationship between two continuous, or interval/ratio level variables; To predict values of a dependent variable based on values of an independent variable.
Background image of page 4
Comparing Continuous Measures Tools to examine the relationship between two continuous variables Visual representation: scatterplot Measure of linear association: correlation Predictive linear model: regression Can be elaborated to address more than one independent variable
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Relationship between independent and dependent variable must be linear; Examining a scatterplot of your data will help you decide if regression analysis is appropriate. Things to Consider:
Background image of page 6
Scatterplots Scatterplots: A method for visually representing the relationship between two continuous variables Like histograms, they have an X and Y axis Histograms: Y-axis reflects frequency of X Scatterplots, in contrast, use X and Y axes to locate a case along two different variables If you suspect that one variable is dependent Use the X axis for the independent variable , Y axis for the dependent variable
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Scatterplots Example: Study time and student achievement. X variable: Average # hours spent studying per day Y variable: Score on reading test Case X Y 1 2.6 28 2 1.4 13 3 .65 17 4 4.1 31 5 .25 8 6 1.9 16 Y axis 0 1 2 3 4 Case 6 is placed at 1.9 on the X- axis, and 16 on the Y-axis 16 1.9
Background image of page 8
Interpreting Scatterplots No relationship is represented by a “cloud” of evenly distributed points Strong linear relationships are reflected by visible “diagonal lines” on the graph Non-linear (curved) relationships are reflected by various curved patterns U-shaped, upside down U-shaped S-shaped, J-shaped
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 8 10 12 14 16 18 20 Educ 30 40 50 60 70 80 P r e s t R’S OCCUPATIOAL PRESTIGE SCORE R’S HIGHEST YEAR OF EDUCATION Scatterplot: Respondent’s Education and Occupational Prestige Score
Background image of page 10
5.0 10.0 15.0 20.0 25.0 30.0 70 75 80 85 90 95 Percent of Women Aged 50-69 who had a Mammogram Percent of Women Who Lack Health Insurance Scatterplot: Health Insurance and Had a Mammogram
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 12
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 14
The Seniority-Salary Relationship
Background image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 16
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 46

Chapter 13 A - Chapter 13 Correlation and Regression...

This preview shows document pages 1 - 16. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online