# FAQ: Isn't the sensitivity function the same as the function used for steady state error? How are they related?

From FBSwiki

*Posted by Asa Hopkins, 22 November 2002*

Yes, the sensitivity function is the transfer function from the reference to the error, which we evaluate at s=0 to determine the steady-state error. More generally, this function tells us about tracking error at whatever frequency -- the steady state error is just the tracking error at zero frequency.