Statistics and supermetallicity: The metallicity of NGC 6791

For the old galactic cluster NGC 6791, Peterson & Green (1998a) and Chaboye r et al. (1999) have found that [Fe/H] similar to +0.4 dex. A second look a t that conclusion is taken in this paper. Zero-point problems are reviewed for a high-dispersion analysis done by Peterson & Green, and it is found th at accidental errors have not been determined rigorously for the results of that analysis. It is also noted that in a color-magnitude analysis perform ed by Chaboyer et al., the important metallicity range between 0.0 and +0.3 dex is not explored and hence is not ruled out. Moreover, that analysis do es not yield statistically rigorous results, and it appears that such resul ts may not be produced in color-magnitude analysis of clusters in general. Results in the two cited papers and elsewhere are re-evaluated statisticall y, with an allowance being made for uncertainty in the cluster reddening. A pparently the best that can be said at present is that the cluster metallic ity lies in the range from +0.16 to +0.44 dex. This conclusion is stressed by reviewing the immaturity of the underlying data base. The premature conc lusion for a high metallicity turns out to be due largely to neglect of acc idental errors, though a tendency to ascribe too much weight to high derive d metallicities may also play a role.