For the old galactic cluster NGC 6791, Peterson & Green (1998a) and Chaboyer et al. (1999) have found that [Fe/H] similar to +0.4 dex. A second look at 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 that accidental errors have not been determined rigorously for the results of that analysis. It is also noted that in a color-magnitude analysis performed 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 does not yield statistically rigorous results, and it appears that such results may not be produced in color-magnitude analysis of clusters in general. Results in the two cited papers and elsewhere are re-evaluated statistically, with an allowance being made for uncertainty in the cluster reddening. Apparently the best that can be said at present is that the cluster metallicity 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 conclusion for a high metallicity turns out to be due largely to neglect of accidental errors, though a tendency to ascribe too much weight to high derived metallicities may also play a role.

Using both high-dispersion and low-resolution data, the metallicities of nine old moving groups and superclusters are analyzed. These stellar groupings include the HR 1614 and Hyades superclusters and the Wolf 630, zeta Her, 61 Cyg, HR 1614, sigma Pup, eta Cep, and Arcturus groups. Samples of these stellar groupings are drawn from Eggen's membership lists. Precautions are taken against problems posed by reddening, visual and spectroscopic binaries, and typographical errors in Eggen's lists. When required, the analyses allow for systematic differences between low-resolution and high-dispersion metallicities. It is found that none of the stellar groupings have the small metallicity dispersion found for a selection of galactic clusters. Instead, the metallicity dispersions turn out to be comparable to the dispersion for a random selection of field stars. For most of the stellar groupings, it does not seem possible at present to learn more by analyzing metallicities. However, one can be more definite about three of them: the HR 1614 supercluster, the HR 1614 group, and the Hyades supercluster. Using a membership list from Eggen (1998c) that is based on Hipparcos astrometry, no evidence is found for the existence of an HR 1614 supercluster. To isolate an HR 1614 group, results from a kinematic analysis (Dehnen 1998) are then used to select a tentative list of members from Eggen's group and supercluster lists. From the mean metallicity of the redefined group, it is found that the group is very unlikely to be a random, magnitude-limited sample of stars. A similar result is obtained for a version of the Hyades supercluster derived from 18 of Eggen's membership lists. About 43% of the stars in this version turn out to be members of the supercluster.

Metallicity calibrations of low-resolution parameters are potentially useful for (at least) two problems: the properties of moving groups, and the supermetallicity problem in K giants. In this paper, metallicity calibrations are derived for six sets of parameters. One of these parameters is the DDO CN index delta CN. This parameter and three others are calibrated for use with evolved G and K stars. Two additional sets of low-resolution parameters are calibrated for use with G and K dwarfs. The calibrations are derived by comparing the input data with two catalogs of homogenized high-dispersion results from diverse authors (see Taylor 1995, 1999a). Using rms errors that are given in the catalogs, intrinsic rms errors are derived for metallicities deduced from the calibrations. The errors turn out to be comparable to those that apply for averaged high-dispersion results.

This paper is one of a series based on published values of [Fe/H] for late-type evolved stars. Only values of [Fe/H] from high-dispersion spectroscopy or related techniques are used. The narrative in this paper begins at a point where mean values of [Fe/H] have been derived for epsilon Vir, alpha Boo, beta Gem, and the Hyades giants. By using these stars as standard stars when necessary, a zero-point data base is assembled. This data base is then expanded into its final version by correcting and adding additional data in a step-by-step process. As that process proceeds, data comparisons are used to establish rms errors. Derived rms errors per datum are found to be about 0.10 - 0.12 dex, and they appear to be too large to be explained by line-to-line scatter and temperature effects.

A catalog of mean values of [Fe/H] for evolved G and K stars is described. The zero point for the catalog entries has been established by using differential analyses. Literature sources for those entries are included in the catalog. The mean values are given with rms errors and numbers of degrees of freedom, and a simple example of the use of these statistical data is given. For a number of the stars with entries in the catalog, temperatures have been determined. A separate catalog containing those data is briefly described.

This paper is the first in a series based on published values of [Fe/H] for late-type evolved stars. Only results from high-dispersion spectroscopy or related techniques are used. From these data, an "analysis catalog" is to be produced containing mean values of [Fe/H] and accidental errors. Such a catalog was published by Taylor in 1991 and is now to be updated. Basic protocols for selecting and analyzing input values of [Fe/H] are stated here. A procedure is described for calculating preferred temperatures and adjusting input values of [Fe/H] to correspond to those temperatures. Ten other possible [Fe/H] corrections are also mentioned, with three corrections that can be applied being described in some detail. These are (1) corrections for use of nonuniform grids of model atmospheres, (2) corrections for use of solar equivalent widths that are not on the Liege system, and (3) corrections for non-LTE effects.