  How do we appropriately fit a model based on an idealised
Friedmann-Lema\^{}tre Robertson-Walker spacetime to observations made from a
single location in a lumpy Universe? We address this question for surveys that
measure the imprints of the baryon acoustic oscillation in galaxy distribution
and the peak apparent magnitude of the Type Ia supernova. These observables are
related to the cosmological model through the Alcock-Paczy\'{n}ski parameters
and the distance-redshift relation. Using the corresponding inhomogeneous
spacetime expressions of these as observed data, we perform a parameter
inference assuming that the background Friedmann-Lema\^{i}tre Robertson-Walker
model is the correct model of the Universe. This process allows us to estimate
the best fit Hubble rate and the deceleration parameter. We find that the
inferred Hubble rate from the monopole of the Alcock-Paczy\'{n}ski parameters
is in tension with the Hubble rate determined using the distance-redshift
relation. The latter gives the best fit Hubble rate for the cosmological
expansion. The constraint on the Hubble rate from the Alcock-Paczy\'{n}ski
parameters is contaminated by the environment. When the environmental
contribution is restricted to modes in the Hubble flow, we find about (9-12)\%
discrepancy in the Hubble rate. Finally, we comment on the insufficiency of the
method of cosmography in constraining the deceleration parameter.
