  The conventional thermoelectric figure of merit and the power factor are not
sufficient as a measure of thin film quality of thermoelectric materials, where
the power conversion efficiency depends on the film dimensions. By considering
the film size, the effective thermoelectric figure of merit and effective
Seebeck coefficient are introduced to guarantee that the maximum energy
conversion efficiency increases as the effective thermoelectric figure of merit
increases. Similarly, the effective power factor is defined. By introducing
typical material properties for Bi$_2$Te$_3$ and PEDOT, we study the thickness
dependence of the effective figure of merit and the effective power factor.
