  The sensitivity parameter is widely used for quantifying fine tuning.
However, examples show it fails to give correct results under certain
circumstances. We argue that these problems only occur when calculating the
sensitivity of a dimensionful mass parameter at one energy scale to the
variation of a dimensionless coupling constant at another energy scale. Thus,
by mechanisms such as dynamical symmetry breaking etc, the high sensitivity of
the energy scale parameter (\Lambda) to the dimensionless coupling constant can
affect the reliability of the sensitivity parameter through the renormalization
invariant factor of the dimensionful parameter. Theoretically, These phenomena
are similar to the problems associated with the time-varying coupling constant
discovered recently. We argue that, the reliability of the sensitivity
parameter can be improved if it is used properly.
