Model The normal error regression model is as follows: $$ Y_{i}=\beta_{0}+\beta_{1} X_{i}+\varepsilon_{i} $$ where: $Y_{i}$ is the observed response in the $i$ th trial $X_{i}$ is a known constant, the level of the predictor variable in the $i$ th trial $\beta_{0}$ and $\beta_{1}$ are parameters $\varepsilon_{i}$ are independent $N\left(0, \sigma^{2} ight) $ $i=1, \ldots, n$ SP.PB. 194