Errors of fit parameters

When we fit a graph/histogram in ROOT,
we obtain the parameter by par1 = myfunction->GetParameter(1) and the error
is obtained by par1err = myfunction->GetParError(1).
While quoting the value of the fit parameter and its error,
we use par1 and par1err. We treat this par1err as statistical error. Is this correct?
If not, what one should do to obtain the statistical error of the fit value of parameter.

Thank you.