  In this paper, we interpret the dark energy as an effect caused by small
scale inhomogeneities of the universe with the use of the spatial averaged
approach of Buchert. The model considered here adopts the
Chevallier-Polarski-Linder(CPL) parameterizations of the equation of state of
the effective perfect fluid from the backreaction effect. Thanks to the
effective geometry introduced by Larena et. al.\cite{larena2009testing} in
their previous work, we confront such backreaction model with latest type Ia
supernova and Hubble parameter observations, coming out with results that
reveal the difference between the Friedmann-Lema\^{\i}tre-Robertson-Walker
model and backreaction model.
