We have data on the distance covered by irrigation water in a furrow of a field. The data are to be used to relate the distance covered to the time since watering began. The data are given in Table...

We have data on the distance covered by irrigation water in a furrow of a field.

The data are to be used to relate the distance covered to the time since watering began. The data are given in Table 8.28.

(a) Perform a simple linear regression relating distance to time. Plot the residuals against time. What does the plot suggest?

(b) Perform a regression using time and the square of time. Interpret the results. Are they reasonable?

(c) Plot residuals from the quadratic model. What does this plot suggest?