groups. Some of the differences between mortality and morbidity indicators appear to vary by age group. Although various explanations are possible, such as differences in the proportion of recent immigrants across age groups, there is as yet no adequate support for any explanation.
In sorting out the possible discrepancies in group comparisons, measurement and other methodological issues require continued attention. For instance, misclassification has an important effect on statistics for some minority groups; ethnic identification and misidentification therefore need further study. The reliability and comparability of such measures as self-reported health require continued attention. Issues such as the black-white mortality crossover at the oldest ages have received much attention from demographers attempting to sort out the methodological issues. Other examples of apparent crossover, or at least convergence, also exist, as well as cases—such as with black-white morbidity—for which rates do not converge.
For some group and subgroup comparisons, inconsistencies may not be evident simply because of the lack or weakness of data. For older American Indians and Alaska Natives, for instance, higher mortality than average may or may not be a problem: the data are too uncertain to be sure. Levels of disability and specific conditions, such as diabetes, indicate health problems in this population. American Indians and Alaska Natives living on or near reservations appear to be in poorer health than others in the group. The small size of the group, however—150,000 American Indians and Alaska Natives are aged 65 and older—makes national samples less practical, though it should be feasible to study representative samples of those living on or near reservations.
Similar attention may be needed to establish the health status of other selected subgroups. This is especially true of the Hispanic and Asian groups, which are known to be heterogeneous with respect to health. Native Hawaiians, for instance, who appear to have high levels of diabetes, need to be distinguished from other Asians, who are the least likely to die of diabetes among the major groups. Subgroups can be small and costly to study, even if the focus is regional rather than national. Rather than considering all subgroups, the focus should be on subgroups that theory and prior research suggest are in substantially poorer health than the general population. As much use as possible should be made of existing data sets.
Research Need 3: When particular diseases are especially prevalent for specific racial and ethnic groups, collect more indicators of biological and functional performance in order to identify possibilities for intervention.
One area of functioning that deserves attention is differences among groups in cognitive ability and other aspects of mental health. Research would require development of measurement approaches that take account