Chapter 2 of 5
Measuring the Errors
How do we know if a line is good or bad?
The gaps between each dot and the line — those are errors (residuals).
* The true errors are random and unobservable. Residuals are estimates of the true error.
Some errors are positive, some negative. It's difficult to quantify the error magnitude.
Sum of errors = +73
(If we sum the error, negative errors cancel out positive errors)
What we can do: Square each error. Now they're all positive. We can sum them to measure the error.
Drag the line. Watch the total squared error change. Can you minimize it?
SSE: Sum of squared error
Your SSE 0
Best possible: 182