Comparison of the photo-z solutions for the 77 common sources in the XMM-COSMOS field. Left: differences in the photo-z solutions found by the ALHAMBRA and COSMOS photometry as a function of the visual magnitudes in the ALHAMBRA filter A678M. Both surveys agree for ~90% of the sources when (z_{PHOT − COS} − z_{PHOT − ALH})/1 + z_SPEC ≤ 0.15, where z_{PHOT − COS} and z_{PHOT − ALH} are the photo-z solutions found in the COSMOS and ALHAMBRA surveys respectively. Right: comparison of the source-by-source photo-z accuracy for both surveys. The threshold limit for outliers, |Δz|/(1 + z_spec) ≤ 0.15, is indicated by vertical and horizontal dashed lines for the COSMOS and ALHAMBRA surveys, respectively. The central grey square represent the region where the two surveys agree, while sources in any of the exterior 4 quadrants (A, B, C, and D) have wrong photo-z solution in both COSMOS and ALHAMBRA (crosses). Sources within the vertical or horizontal stripes, defined by the dashed lines, and not within the central square have either i) good-COSMOS and poor-ALHAMBRA solutions (squares) or ii) good-ALHAMBRA and poor-COSMOS solutions (diamonds).