The world’s Largest Sharp Brain Virtual Experts Marketplace Just a click Away
Levels Tought:
Elementary,Middle School,High School,College,University,PHD
| Teaching Since: | May 2017 |
| Last Sign in: | 408 Weeks Ago |
| Questions Answered: | 66690 |
| Tutorials Posted: | 66688 |
MCS,PHD
Argosy University/ Phoniex University/
Nov-2005 - Oct-2011
Professor
Phoniex University
Oct-2001 - Nov-2016
8   Consider the standard simple regression model y 5 b0 1 b1x 1 u under the Gauss-Markov Assumptions SLR.1 through SLR.5. The usual OLS estimators bˆ and bˆ are unbiased for
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1
their respective population parameters. Let b˜      1 be the estimator of b1 obtained by assuming
the intercept is zero (see Section 2.6).
(i)      Find E(b˜1) in terms of the xi, b0, and b1. Verify that b˜ 1 is unbiased for b1 when the population intercept (b0) is zero. Are there other cases where b˜ 1 is unbiased?
(ii)Â Â Â Â
|
Find the variance of b˜ 1. (Hint: The variance does not depend on b0.)
(iii)Â Â Â
|
|
Show that Var(b˜ 1) # Var(b1). [Hint: For any sample of data,
∑i51 (x 2 x¯) , with strict inequality unless x¯ 5 0.]
Â
n
i51
Â
xi 
Â
n                       2
i
(iv)  Comment on the tradeoff between bias and variance when choosing between bˆ and b˜ .
1Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1
                                                 Â
Hel-----------lo -----------Sir-----------/Ma-----------dam-----------Tha-----------nk -----------You----------- fo-----------r u-----------sin-----------g o-----------ur -----------web-----------sit-----------e a-----------nd -----------acq-----------uis-----------iti-----------on -----------of -----------my -----------pos-----------ted----------- so-----------lut-----------ion-----------.Pl-----------eas-----------e p-----------ing----------- me----------- on-----------cha-----------t I----------- am----------- on-----------lin-----------e o-----------r i-----------nbo-----------x m-----------e a----------- me-----------ssa-----------ge -----------I w-----------ill----------- be-----------