Chapter 2- Looking at Data
•we often care about the relationship between two variables
•to study the relationship, we measure both variables on the same individuals
Two variables measured on the same individuals are associated
if some values of one
variable tend to occur more often with some values of the second variable than with other
values of that variable.
EX- taller people tend to be heavier
EX- people who smoke a lot of cigarettes tend not to live as long as those who do not
response variable
- measures an outcome of a study
explanatory variable
- explains or causes change in the response variables
independent variables
- explanatory variables
dependent variables
- response variables
Many explanatory-response variables do not involve direct causation.
EX- SAT scores predict future college grades.
SAT scores, however, don’t have a causal
impact on college gpa.
This
preview
has intentionally blurred sections.
Sign up to view the full version.
2.1 Scatterplots
scatterplot
- shows the relationship between two
quantitative
variables measured on the
same individuals

This is the end of the preview.
Sign up
to
access the rest of the document.
- Spring '11
- Bill
- explanatory variables, response variables, above-average values
-
Click to edit the document details