Chapter 13 A

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

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

Chapter 13 Correlation and Regression

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

View Full Document
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
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

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

View Full Document
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.
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

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

View Full Document
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:
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

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

View Full Document
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
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

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

View Full Document
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
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

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

View Full Document

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

View Full Document
The Seniority-Salary Relationship

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### 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
Ask a homework question - tutors are online