In the beginning paragraph on page 121402-7 there is an error in language with regards to the sign of the estimated coefficient for gallons per mile (gpm). The estimated coefficient is positive and not negative. However, the stated conclusions are based on interpretation of the correct sign and remain unchanged.
Additional edits to the unit labels in Appendix D have been updated in the supplementary material found in the website.1
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Finally, we observe that some of the models with the best predictive accuracy have coefficients with unexpected signs—likely biased due to correlation with unobserved attributes. Despite good prediction accuracy in existing markets, where attribute correlations are similar from year to year, these models may misguide design efforts if the designer makes changes that do not follow correlations in the marketplace. For example, the sign of the coefficient for the gallons per mile (gpm) attribute of the...
