  This paper presents the results of a systematic study of projection biases in
the Weak Lensing analysis of cosmic shear and the combination of galaxy
clustering and galaxy-galaxy lensing using data collected during the first-year
of running the Dark Energy Survey experiment. The study uses $\Lambda$CDM as
the cosmological model and two-point correlation functions for the WL analysis.
The results in this paper show that, independent of the WL analysis, projection
biases of more than $1\sigma$ exist, and are a function of the position of the
true values of the parameters $h$, $n_{s}$, $\Omega_{b}$, and
$\Omega_{\nu}h^{2}$ with respect to their prior probabilities. For cosmic
shear, and the combination of galaxy clustering and galaxy-galaxy lensing, this
study shows that the coverage probability of the $68.27\%$ credible intervals
ranges from as high as $93\%$ to as low as $16\%$, and that these credible
intervals are inflated, on average, by $29\%$ for cosmic shear and $20\%$ for
the combination of galaxy clustering and galaxy-galaxy lensing. The results of
the study also show that, in six out of nine tested cases, the reduction in
error bars obtained by transforming credible intervals into confidence
intervals is equivalent to an increase in the amount of data by a factor of
three.
