  Using the invariance of Quadratic Gravity in FLRW metric under the group of
diffeomorphisms of the time coordinate, we rewrite the action $A$ of the theory
in terms of the invariant dynamical variable $g(\tau)\,.$
  We propose to consider the path integrals $\int\,F(g)\,\exp\left\{-A
\right\}dg$ as the integrals over the functional measure
$\mu(g)=\exp\left\{-A_{2} \right\}dg\,,\ $ where $A_{2}$ is the part of the
action $A$ quadratic in $R\,.$ The rest part of the action stands in the
exponent in the integrand as the "interaction" term. We prove the measure
$\mu(g)$ to be equivalent to the Wiener measure, and, as an example, calculate
the averaged scale factor in the first nontrivial perturbative order.
