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Linear Regression. Special Topics. Regression Line. A regression line is a straight line that describes how a response variable y changes as an explanatory variable x changes. We often use a regression line to predict the value of y.
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Linear Regression Special Topics
Regression Line • A regression line is a straight line that describes how a response variable y changes as an explanatory variable x changes. • We often use a regression line to predict the value of y. • Regression, unlike correlation, requires that we have an explanatory and a response variable.
Least –Squares Regression Line (LSRL) • The Least Squares Regression Line (LSRL) is a mathematical model suitable for a linear trend. • LSRL - of y on x is the line that makes the sum of squares of the vertical distance of the data points to the line as small as possible. (error) • error = observed – predicted
Demonstration • http://hadm.sph.sc.edu/courses/J716/demos/LeastSquares/LeastSquaresDemo.html • LSRL equation: = mx + b • is the predicted response • bis the y-intercept • mis the slope
Homework • Worksheet