A British survey just revealed that the New York Yankees baseball team pays their players, on average,

Question:

A British survey just revealed that the New York Yankees baseball team pays their players, on average, more than any other team in the world (sportsillustrated.cnn.com, April 7, 2010). Brendan Connolly, a statistician for a Major League Baseball (MLB) team, wants to elaborate on the salary of baseball players. Excluding pitchers from his analysis, he believes that a baseball player's batting average (BA), runs batted in (RBI), and years of experience playing professional baseball (Experience) are the most important factors that influence a player's salary. Further, he believes that salaries rise with experience only up to a point, beyond which they begin to fall; in other words, experience has a quadratic effect on salaries. Brendan collects data on salary (in $1,000s), BA, RBI, and experience for 138 outfielders in 2008. A portion of the data is shown in the accompanying table.

In a report, use the sample information to:
1. Estimate a quadratic regression model using Salary as the response variable and BA, RBI, Experience, and Experience2 as the explanatory variables.
2. Compare the above quadratic regression model with a linear model that uses BA, RBI, and Experience as the explanatory variables.