  The purpose of this mock data and science challenge is to prepare the data
analysis and science interpretation for the second generation of
gravitational-wave experiments Advanced LIGO-Virgo in the search for a
stochastic gravitational-wave background signal of astrophysical origin. Here
we present a series of signal and data challenges, with increasing complexity,
whose aim is to test the ability of current data analysis pipelines at
detecting an astrophysically produced gravitational-wave background, test
parameter estimation methods and interpret the results. We introduce the
production of these mock data sets that includes a realistic observing scenario
data set where we account for different sensitivities of the advanced detectors
as they are continuously upgraded toward their design sensitivity. After
analysing these with the standard isotropic cross-correlation pipeline we find
that we are able to recover the injected gravitational-wave background energy
density to within $2\sigma$ for all of the data sets and present the results
from the parameter estimation. The results from this mock data and science
challenge show that advanced LIGO and Virgo will be ready and able to make a
detection of an astrophysical gravitational-wave background within a few years
of operations of the advanced detectors, given a high enough rate of compact
binary coalescing events.
