How do you know when to calculate standard error of the estimate?

Question

Here is the question : I am given the regression line equation y'= 33.114 +0.487 x . The correlation coefficient is r = 1.000. Compute the standard error of the estimate , if appropriate. Assume that alpha = .05 using graphing calulator.

Basically I would like to know when should I know to calculate standard error of the estimate ? Like what do I look for in order to calculate it please?

Answer 1

If the R = 1.000 then that means there is no error. All the points fall exactly on a line. You would/could calculate error for any regression where the R is not 1.000 or -1.000