In Example 6 we used data from 1920 to 2020 and found that the life span in the United States depended on the year of birth according to the equation
L(x) = 11.027 + 14.304 ln x
where x is the number of years after 1900. Using data from 1920 to 1989, the model
ℓ(x) = 11.616 + 14.144 ln x
where x is the number of years after 1900, predicts life span as a function of birth year. Use both models to predict the life spans for people born in 1999 and in 2015. Did adding data from 1990 to 2020 give predictions that were quite different from or very similar to predictions based on the model found earlier?