In Chapter 7, we found a relationship between the age of a bridge in Tompkins County, New York, and its condition as found by inspection. (Data in Tompkins County Bridges 2016) But we considered only bridges built or replaced since 1900. Tompkins County is the home of the oldest covered bridge in daily use in New York State. Built in 1853, it was recently judged to have a condition of 4.57. Here is a regression of Condition on the year in which a bridge was Built, computed for bridges built since 1900.

a) If we use this regression to predict the condition of the covered bridge, what would its residual be?
b) If we add the covered bridge to the data, what would you expect to happen to the regression slope?

c) If we add the covered bridge to the data, what would you expect to happen to the R²?
d) The bridge was extensively restored in 1972. If we use that date instead as the Built date, do you find the condition of the bridge remarkable?

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Dependent variable is Condition R-squared = 48.1% = 0.6311 Variable Intercept Built Coefficient -37.1251 0.0215