SECTION 5E HIGHLIGHTS
Vocabulary: Correlation, Scatter Diagram, Positive Correlation, Negative Correlation, Causality, Coincidence, Common Underlying Cause, Direct Cause.
Assignment: Read about Correlation and Causality in Section 5E of the text. Do pp. 371-375 RQ(1,3), EX(17-26, 31-36), WP(42).
Web Project #42 Link: STATISTICAL ABSTRACTS OF THE UNITED STATES
Spreadsheet containingTables 5.6 and 5.7 from text
Spreadsheet for Homework Exercises #25 and #26
Notes:
A correlation exists between two variables when higher values of one variable consistently go with higher values of the other variable or when higher values of one variable consistently go with lower values of the other variable.
Scatter diagrams can be used to spot correlation between two variables.
CORRELATION
APPLET
The textbook describes the following as possible relationships between two
data variables:
1. No correlation - No apparent relationship between the two variables.
2. Positive correlation - Both variables tend to increase(decrease) together.
3. Negative correlation - Two variables tend to change in opposite directions,
with one increasing while the other decreases.
The Strength of a correlation is determined by how closely the two variables follow the general trend. In a perfect correlation, all data points fall on a straight line.
There are three possible explanations for a Correlation given in the text. They are:
1. The correlation may be merely a coincidence.
2. The correlated effects may have a common underlying cause.
3. One of the correlated effects may be the cause of the other.
Skills to be mastered:
1. The student should be able to indicate if a correlation occurs
because of coincidence, because of an underlying cause, or because one is the
cause of the other.
2. The student should be able to categorize a correlation as positive or
negative.
3. The student should be able to create and interpret a scatter diagram.
4. The student should be able to distinguish between correlation and
causality.