  The Kepler Mission was designed to measure the frequency of Earth-size
planets in the habitable zone of Sun-like stars. A crucial component for
recovering the underlying planet population from a sample of detected planets
is understanding the completeness of that sample - what fraction of the planets
that could have been discovered in a given data set were actually detected.
Here we outline the information required to determine the sample completeness,
and describe an experiment to address a specific aspect of that question, which
is the issue of transit signal recovery. We investigate the extent to which the
Kepler pipeline preserves individual transit signals by injecting simulated
transits into the pixel-level data, processing the modified pixels through the
pipeline, and comparing the measured transit signal-to-noise ratio (SNR) to
that expected without perturbation by the pipeline. We inject simulated transit
signals across the full focal plane for a set of observations of length 89
days. On average, we find that the SNR of the injected signal is recovered at
MS = 0.9973(+/-0.0012)xBS-0.0151(+/-0.0049), where MS is the measured SNR and
BS is the baseline, or expected, SNR. The 1{\sigma} width of the distribution
around this correlation is +/-2.64%. We discuss the pipeline processes that
cause the measured SNR to deviate significantly from the baseline SNR; these
are primarily the handling of data adjacent to spacecraft re-pointings and the
removal of harmonics prior to the measurement of the SNR. Finally we outline
the further work required to characterise the completeness of the Kepler
pipeline.
