We should not extrapolate that far beyond the range of the data. The decreasing trend in winning times cannot continue at the same rate forever, and it may not still apply by the year 2002. The relationship that held for the distances of 5 to 15 feet obviously does not extend to distances as short as 2 feet or as long as 20 feet. It is not appropriate to assume that relationships continue to hold beyond the range of the data observed. The relationship is a curve that looks like an elongated, tilted letter C. d.
Regression lines work only for straight line relationships.
Clearly, the relationship between success and distance over the entire range from 2 feet to 20 feet is curved, not linear. The strength of the relationship is the same as for the golfers and the sample is much larger.