RAND Corporation

About: RAND Corporation is a nonprofit organization based out in Santa Monica, California, United States. It is known for research contribution in the topics: Health care & Population. The organization has 9602 authors who have published 18570 publications receiving 744658 citations.

The Numerical Simulation of Ice-Age Climate with a Global General Circulation Model.

Abstract: The global distribution of July climate has been simulated with a two-level atmospheric general circulation model using the surface boundary conditions of sea-surface temperature, ice-sheet topography and surface albedo assembled by CLIMAP for 18 000 years before present. These conditions respresent an approximate doubling of the ice-covered surface area of the earth, a 1°C decrease of the average sea-surface temperature, and an increase of the average surface albedo from 0.14 to 0.22. Compared with the simulation of present July conditions, the ice-age atmosphere is found to have been substantially cooler and drier, especially over the continents of the Northern Hemisphere, corresponding to an enhanced anticyclonic circulation over the major ice sheets and a general weakening of the summer monsoonal circulation. The midlatitude westerlies are strengthened and systematically displaced southward in the vicinity of the major ice sheets, along with an equatorward shift in the zones of maximum eddy a...

Return and other sequences of migration in the United States

Abstract: We examine repeat migration sequences in the United States especially those that entail a return, using data from the Panel Study of Income Dynamics. Our guiding hypotheses derive from the concepts of location-specific capital and imperfect information. Descriptive analysis elucidates the dynamics, tempo, and differential frequency of repeat migration among various socioeconomic groups. Results disclose differences among migrants who choose to return or move onward to a new location, or do not move again, and lend support to our analytical framework. Major findings are: (1) the propensity to return to an area varies directly with the amount of locationspecific capital that is left behind and inversely with the ex-resident’s length of absence, (2) which repeat migration sequence unfolds—return or onward—depends on the ex-resident’s educational level and experience of unemployment.

Explaining adult age differences in decision‐making competence.

Abstract: Studies on aging-related changes in decision making report mixed results. Some decision-making skills decline with age, while others remain unchanged or improve. Because fluid cognitive ability (e.g., reasoning, problem solving) deteriorates with age, older adults should perform worse on decision-making tasks that tap fluid cognitive ability. However, performance on some decision-making tasks may require experience, which increases with age. On those tasks, older adults should perform at least as well as younger adults. These two patterns emerged in correlations between age and component tasks of Adult Decision-Making Competence (A-DMC), controlling for demographic variables. First, we found negative relationships between age and performance on two tasks (Resistance to Framing, Applying Decision Rules), which were mediated by fluid cognitive ability. Second, performance on other tasks did not decrease with age (Consistency in Risk Perception, Recognizing Age-group Social Norms) or improved (Under/Overconfidence, Resistance to Sunk Costs). In multivariate analyses, performance on these tasks showed independent positive relationships to both age and fluid cognitive ability. Because, after controlling for fluid cognitive ability, age becomes a proxy for experience, these results suggest that experience plays no role in performing the first set of tasks, and some role in performing the second set of tasks. Although not all decision-making tasks showed age-related declines in performance, older adults perceived themselves as worse decision makers. Self-ratings of decision-making competence were related to fluid cognitive ability and to decision-making skills that decreased with age—but not to decision-making skills that increased with age. Copyright © 2010 John Wiley & Sons, Ltd.