Chapter 3 and 4 Flashcards
What would a correlation of 1, 0, -1 look like
1 and -1 would be perfect lines, 0 would have no linear relationship
What is the difference between categorical and quantitative variables
Quantitative can be measured in numbers and categorical is in categories (race, gender, occupation)
What is the purpose of the least squared regression line
To determine a line of best fit by minimizing the sum of squares. A square is determined by squaring the distance between a data point and the regression line
What is the equation for slope
R(sy/sx)
What is the equation for the intercept
_ _
A: y-bx
What is the least squared regression line equation
Y= a+bx
What does r2 represent
The fraction of the variation that is explained by the regression
What is extrapolation
The use of a regression line for prediction far outside the range of values of x
What is a lurking variable
A variable that has an important effect on the relationship among the variables in a study but is not included among the variables studied
What is a residual
A numerical value for how much went wrong; a difference between an observed value of the response variable and the value predicted
What is an influential point
An outlier that greatly affects the slope of the regression line
Define causation
Cause and effect line between two variables
Define common response
The observed association between x and y is explained by a lurking variable z
Define confounded
Two variable’s effects on a response variable are mixed together
How do we show causation if an experiment is not possible
- The association is strong and consistent
- The alleged cause precedes the effect in time
- It is plausible
- Higher doses are associated with higher responses
