Consider the following model: \[ y_i=f(x_i)+\epsilon _i,\qquad 1\leq i\leq n, \] where \[ f(t)=a_0+a_1t+\cdots +a_pt^p. \] The parameters \(a_0,a_1,\ldots ,a_p\) are unknown. The errors \(\epsilon _1,\epsilon _2,\ldots ,\epsilon _n\) are independent normal \(N(0,\sigma ^2)\) random variables. It is assumed that \(x_i\in [0,1]\) and known. We observe \((y_i,x_i)\), \(1\leq i\leq n\).
- Estimate the parameters \(a_0,a_1,\ldots ,a_p\) and \(\sigma ^2\). (15 points)
- Get the distribution of the estimator for \(\sigma ^2\). (5 points)