Linear Regression Models (3)

http://www.geocities.com/asdfasdf23135/stat20.JPG

http://www.geocities.com/asdfasdf23135/stat21.JPG

3) **"A linear regression model is of the form:**

**Y = β0 + (β1)(X1) + (β2)(X2) + ... + (βk)(Xk) + ε**

**If there is more than one independent variable, then the model is called a MULTIPLE linear regression model."**

This idea doesn't seem too clear to me. Here, what can the Xi's be? What are some specific examples of mutliple linear model? Does a linear model always have to be a straight line or a plane?

Thanks for clearing my doubts!

β

ε

note: also under discussion in "Talk Stats Forum"