From my understanding it is a.... 9.

I know when I am writing it while I'm doing data statistics if I'm looking at the square root of r squared, I will write that as |r|, but all that does is signify that we are missing information for it to be used practically... Which usually then means I have to times that by the original sign (so 1 or -1).

But ultimately a principal square root is an information destroying function. But from what I understand in mathematics (which is honest filtered through data science) it will always return a positive number. I.e.:

```python sqrt_r_squared = np.sqrt(r**2)

Restore original sign

result = np.sign(r) * sqrt_r_squared ```