introduce a spurious constant shear. The aperture mass statistic, being computed with a compensated filter, is unaffect by a constant shear, which is the main reason for choosing this statistic for the present analysis. In contrast, a constant shear affects top-hat two-point statistics. The impact of redshift-dependent additive and multiplicative shear biases, which are present in all KSB-based shear estimators, on cosmological constraints is studied in Semboloni [et al. ]{}(2008).

### Joint analysis

In the joint analysis, we adopt the [*importance sampling*]{} technique [@hastings70; @lewisbridle], adding CFHTLS-T0003 cosmic shear data to two Monte Carlo Markov chains available in the [Lambda]{} archive[^3] for the mixed dark-matter scenario. One of the chains was computed for CMB temperature and polarization anisotropies derived from WMAP-5yr [@wmap5dunkley] data. The other chain used a combination of these data with baryon acoustic oscillations from SDSS and 2dFGRS [@baodata], and Type Ia supernovae from the “Gold” sample [@sngold] and SNLS [@snls].

Importance sampling consists of estimating a target distribution (a joint posterior distribution in our case) by sampling an auxiliary distribution. We assume that the public Monte Carlo Markov chains provided by the WMAP team have enough resolution at the region of parameter space intersecting the cosmic shear 