  An expression for the energetic efficiency of a molecular motor is presented
in terms of an effective temperature, which was defined based on the ratio of
the correlation function to the susceptibility of its velocity. We also present
a numerical result regarding this temperature for a thermal ratchet model.
Furthermore, our expression of efficiency using known values for kinesin can
adequately explain the experimental results. The framework presented here has a
closed form phenomenologically, and is independent of any detailed models.
