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Q57Section I (Objective (Q1–Q80))57 of 80

Nested models and residual sums of squares

Model-I: Y=β0+β1XY=\beta_0+\beta_1X and Model-II: Y=β0+β1X+β2X2Y=\beta_0+\beta_1X+\beta_2X^2 are fitted for the data set (Xi,Yi);i=1,2,…,n(X_i,Y_i); i=1,2,\dots,n. Denote β^0\hat\beta_0 and β^1\hat\beta_1 as least square estimates of β0,β1\beta_0,\beta_1 from Model-I, and β0∗,β1∗,β2∗\beta_0^*,\beta_1^*,\beta_2^* be the least square estimates from Model-II. Define P=∑i=1n(Yi−β^0−β^1Xi)2P=\sum_{i=1}^n(Y_i-\hat\beta_0-\hat\beta_1X_i)^2 and Q=∑i=1n(Yi−β0∗−β1∗Xi−β2∗Xi2)2Q=\sum_{i=1}^n(Y_i-\beta_0^*-\beta_1^*X_i-\beta_2^*X_i^2)^2. Consider the following statements:

I. P≥QP\ge Q

II. It can happen that Q=0Q=0 but P>0P>0.

Which of the statements given above is/are correct?

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