than the photo-z results of codes tested in @Dahlen13, where the photometry used comprised 14 bands including full depth CANDELS and Spitzer data.

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\[figure:som\_update\]

While the performance we find is quite good, and may be representative of what can be achieved with a survey such as *Euclid* or *WFIRST*, the results depend on the depth and stability of the photometry. The photometry used to place objects on the SOM in order to estimate a photo-z in the above analysis is quite deep ($i$-band depth $\sim$25.4 AB). The results will degrade as the photometry gets shallower or bands are lost in a manner that can be directly characterized via the SOM. A detailed study of the expected performance from the SOM-based photo-z approach will be the subject of a future paper.

Outliers
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Out of 1079 sources with Q=4 redshifts and reliable SOM-based photo-z estimates, only 41 (3.8%) are outliers according to the standard definition, $\lvert z_{p} - z_{s} \rvert/(1+z_{s}) \geq 0.15$. If, instead of the SOM-based photo-z, we use the photo-z for each object based on deep multiband data (e.g., the 30-band COSMOS data), we find an outlier fraction for the same sources of 