QuESTION $1$: NETFLIX RECOMMENDATION $(40$ POINTS$)$

For this question, you have the option to pick either Q$1\mathrm{.}1$ by doing detailed calculations by handwriting, or Q$1\mathrm{.}2$ by programming. Either way, you will get the full grade.And by doing both, there will be NO extra points.

Q$1\mathrm{.}1(40$ points$)$ Consider a $($very small$)$ set of four users $($A $-$ D$)$ and three movies $($I $-$ III$),$ with ratings as indicated below. The test set is denoted with bold and blue, and the unknown entries have $"?".$

$1.$ Calculate the predictor from raw averaging.

$2.$ What is the RMSE on the test set for the raw average predictor?

$3.$ What are the biases for Movie I and User D$?$

$4.$ Calculate the baseline predictor.

$5.$ What is the RMSE on the test set for the baseline predictor?