 From the standpoint of public health policymaking, there are several other problems with natural measures of population health, like life expectancy or infant survival rates. These measures cannot provide a summary picture of the overall state of health or burden of ill health of a population, nor do they allow for comparison of the value or impact of alternative investments in different health priorities. The latter is a particular problem for allocating health budgets and setting priorities for funding. Although classic cost-benefit analysis provides a solution that admits of comparisons across diverse health areas and outcomes, reducing all the benefits and risks at issue in public health to their monetary value is widely viewed as unsatisfactory. In response, a series of summary measures of population health have been developed that seek to reduce into one fungible metric both life expectancy and considerations of impact of disease and of medical interventions on function and disability. Operating out of the preference-satisfaction tradition, well-known summary metrics include Quality Adjusted Life Years (QALYs), Disability-Adjusted Life Years (DALYs), Disability-Adjusted Life Expectancy (DALE) and Healthy Life Year (HeaLY). Summary measures have been subject to extensive ethics critique. (See the entry on  disability and health care rationing.)  Some of these criticisms reflect difficulties with conceptualizing and operationalizing utility accounts of welfare. For example, these measures sometimes rely on assessments of what may be only vague individual preferences for trade-offs between different states of health or different kinds of benefits, or trade-offs made by samples of persons that are viewed as too narrow. These summary measures have also been critiqued to the extent that they rely on average trade-off assessments that may mask wide disagreement about the disvalue of a compromised health state.