Unit 2 - Linear Regression Flashcards
What is y hat?
Predicted y value
What is the formula for the slope of a regression line?
a = r(sy/sx)
What is an influential point?
A point, when removed, significantly changes the regression equation.
Given a scatterplot, how can you tell if a linear model is appropriate?
The scatterplot shows a linear pattern.
Given a residual plot, how can you tell if a linear model is appropriate?
The residual plot shows no pattern.
Where can you find residuals on your calculator?
2nd STAT (List), 7: RESID
Correlation will always be a number between ___ and ____.
1 and -1
What does LSRL stand for?
Least Squares Regression Line
What are the characteristics of a least squares regression line?
- It contains the point (x-bar, y-bar)
- The sum of the residuals is zero.
- The sum of the squares of the residuals is the least number possible.
Which correlation is stronger? .4 or - .5
-.5
What is the formula for the least squares regression line?
y-hat = b + ax
What is a residual?
The distance between a point and the regression line.
What is the formula for a residual?
e = y-hat - y
What is extrapolation?
Using a regression model to make a prediction outside the range of data collected.
What is interpolation?
Using a regression model to make a prediction within the range of data collected.
Given this equation, interpret the slope.
Globs-hat = 20 + 1.5 blags
For every increase in 1 blag, the number of globs increases by approximately 1.5.
Given this equation, interpret the y-intercept.
Globs-hat = 20 + 1.5 blags
When there are zero blags, the number of globs is predicted to be 20.
Explanatory Variable = calories
Response Variable = weight
R-sq = 82.3%
Interpret R-sq
82.3% of the variation in weight can be explained by the number of calories eaten.
Describe a scatterplot with a correlation coefficient of r = -.5.
There is a moderate, negative, linear association between x and y.
What is the formula for a residual?
e = y - yhat
