The dataset below contains team performance data from Major League Baseball for several seasons.$\text{'}$

Retain all work that you do to answer the questions below.

Notes on variables: RS $=$ Runs Scored, RA $=$ Runs Scored Against, W $=$ Wins, OBP $=$ On$-$base percentage

SLG $=$ slugging percentage, BA $=$ batting average. All of these stats are given as team averages.

a$)$ Create a new variable called RD $($for run differntial$).$ RD $=$ RS $-$ RA$.$

b$)$ Of the RS$,$ RA$,$ RD$,$ OBP, SLG$,$ and BA variables, which appears to be the best single predictor of W $($Team wins$)?($Hint: Single predictor means a simple linear regression model$)$

c$)$ Develop the best linear regression model that you can to predict W$.($Bonus point, if you can model League as one of your variables.$)$

Tip: I am aware that excel throws you a #NUM error in a particular instance. In such a case, use your creativity to play around and omit a variable or two to get rid of that error.

d$)$ Interpret your model built in part$-$c in detail. Perform and explain all the necessary significance tests.