1. ## Nested Models

Going through this concept for the first time. The literature's and teacher's explanations make sense nominally: "Two models are nested if both contain the same terms and one has at least one additional term." "One model is contained within the other."

All of the initial examples are like...

Y(math) = b0 + b1*X(rdg) + b2*X(wrtg)
Y(math) = b0 + b1*X(rdg)

...which is pretty straightforward and easy to understand. Naturally, the homework puts in a wrinkle that I'm not confident in answering.

Y = 10,000 + 150*X1 + 25*X1^2 + 60*X2
Y = 9,750 + 145*X1 + 75*X2

The question is if either model nests the other. I am inclined to answer 'No' because they do not contain the same "term". Problem is, I'm not sure if 'term' means variable or parameter - or the combination of both. But it sure seems like neither model is contained within the other.

2. ## Re: Nested Models

The coefficients don't need to match if that's what you're worried about. Just look at which variables are included in the models.

3. ## The Following User Says Thank You to Dason For This Useful Post:

JTWood (10-18-2014)

4. ## Re: Nested Models

Ah, okay. So the second model nests because it has X1 and X2, but not X1^2.

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