More than one million motorcycles are sold annually (www.webbikeworld.com). Off-road motorcycles (often called “dirt bikes”) are a market segment (about 18%) that is highly specialized and offers great variation in features. This makes it a good segment to study to learn about which features account for the cost (manufacturer’s suggested retail price, MSRP) of a dirt bike. Researchers collected data on dirt bikes. Their original goal was to study market differentiation among brands (Jiang Lu, Joseph B. Kadane, and Peter Boatwright, The Dirt on Bikes: An Illustration of CART Models for Brand Differentiation). We have updated the data and can use it to predict msrp from other variables.
Here are scatterplots of three potential predictors, Wheelbase (in), Displacement (cu in), and Bore (in).

Comment on the appropriateness of using these variables as predictors on the basis of the scatterplots.