1. Unit 4 Vocabulary

2. Scatterplot
The most popular way to display a relationship between 2 quantitative variables

3. Explanatory Variable
Variable that we think explains or causes changes in the response variable

4. Response Variable
A variable that measures an outcome or result of a study

5. Overall Pattern
As in any graph of data, look for the overall pattern and for striking deviations from that pattern

6. To Describe the Pattern of a Scatterplot: DOFS
Direction
Form
Strength
Outliers

7. Correlation
Describes the direction and strength of a straight line relationship between two quantitative variables.
Usually written as r
Memorize this formula

9. Positive Correlation
Above average values of one tend to accompany above average values of the other
Slopes upward as we move from left to right

10. Negative Correlation
Above average values of one tend to accompany below average values of the other
Scatterplot slopes downward from left to right

11. Correlation is ALWAYS Between -1 to 1

12. Regression Line
Straight line that describes how a response variable y changes as an explanatory variable x changes
We use this to predict y

13. Least Squares Regression Line
Y on x is the line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible

14. Slope
The amount by which y changes when x increases by one unit

15. Y-Intercept
Where the line intersects the Y axis

16. Residual
Observed y – predicted y

17. Square of the Correlation
The fraction of the variation in the values of y that is explained by the least-squares regression of y on x

18. Lurking Variable
Variable that has an important effect on the relationship among the variables in a study but is not one of the explanatory variables studied

19. Common Response
Refers to changes in both the explanatory and response variables that result from changes in another variable

20. Confounding
Two variables are confounded when their effects are on a response variable cannot be distinguished from each other