1. In order to deal with a violation of the homoscedasticity assumption is to generalize model, by. permitting, a less restrictive form for the covariance matrix of the error. ..
2. \(x=\operatorname{rnorm}(100,0,3) y=3-2^{*} x+\operatorname{rnorm}\left(100,0, \operatorname{sapply}\left(x\right.\right.\), function \(\left.\left.(x)\left\{1+0.5^{*} x^{\wedge} 2\right\}\right)\right) \ldots\)
3. wght \(<-1 /\left(1+0.5^{*} x^{\wedge} 2\right)\) fit.wls \(=\operatorname{lm}(y \sim x\), weight \(=w g h t)\)