Saving and consumption patterns of the elderly

The paper provides an empirical analysis of saving and consumption choices of the elderly in Germany, based on the German income and expenditure surveys 1978 and 1983. Main feature of these data is the large sample size making it possible to analyze saving and consumption patterns of the very old (aged 75 and above).The observed age-consumption profiles are very different from those predicted by the pure life-cycle theory. Although wealth is declining between age 60 and 70, it increases again after 70, such that the very old have the highest savings rates among all age groups and accumulate wealth rather than decumulate it. These profiles are not confounded by cohort effects and mortality differences. The corresponding expenditure data suggest the following explanation: due to the generous German pension system and the almost complete coverage of health expenses by the mandatory health insurance in Germany, the declining consumption n very old age cannot exhaust the annuity income of the elderly such that wealth is being accumulated in old age.Research in this paper was supported by the National Institute on Aging, grant no. 3 PO1 AG05842-01. I appreciate the helpful comments by Doug Bernheim, Angus Deaton, Daniel McFadden, Jonathan Skinner, Konrad 'Stahl and David Wise, and two anonymous referees. I am indebted to Hermann Buslei and Johannes Velling who provided most valuable and able assistance.     

Origins and destinies: Immigration to the United States since World War II

Contemporary immigration to the United States and the formation of new ethnic groups are the complex and unintended social consequences of the expansion of the nation to its post-World War II position of global hegemony. Immigrant communities in the United States today are related to a history of American military, political, economic, and cultural involvement and intervention in the sending countries, especially in Asia and the Caribbean Basin, and to the linkages that are formed in the process that open a variety of legal and illegal migration pathways. The 19.8 million foreign-born persons counted in the 1990 U.S. census formed the largest immigrant population in the world, though in relative terms, only 7.9% of the U.S. population was foreign-born, a lower proportion than earlier in this century. Today's immigrants are extraordinarily diverse, a reflection of polar-opposite types of migrations embedded in very different historical and structural contexts. Also, unlike the expanding economy that absorbed earlier flows from Europe, since the 1970s new immigrants have entered an hourglass economy with reduced opportunities for social mobility, particularly among the less educated, and new waves of refugees have entered a welfare state with expanded opportunities for public assistance. This paper seeks to make sense of the new diversity. A typology of contemporary immigrants is presented, and their patterns of settlement, their distinctive social and economic characteristics compared to major native-born racial-ethnic groups, and their different modes of incorporation in—and consequences for—American society are considered.     

Statistical consulting at German universities: Results of a survey

The article presents the results of a survey on statistical consulting at German universities, where the survey focused on obtaining information on when, where and to whom statistical consulting is provided. We investigate the financial frame of the activity and question the advantages and disadvantages from a consultant’s point of view.     

A Hausman test for Brownian motion

New tests are proposed for the specification of the intraday price process of a risky asset, based on open, high, low, and close prices. Under the null of a Brownian process we derive two stochastically independent, unbiased volatility estimators. For a Hausman specification test we prove its equivalence with an F-test, consider its robustness against variation in drift and volatility, and analyze the power against an Ornstein–Uhlenbeck process, as well as a random walk with alternative distributions.     

Statistical consulting

The paper and the special issue focus on the activity of statistical consulting and its varieties. This includes academic consulting, consulting to and in industry as well as statistics in public media.     

Bayesian design in queues: An application to aeronautic maintenance

We exploit Bayesian criteria for designing M/M/c//r$M/M/c//r$ queueing systems with spares. For illustration of our approach we use a real problem from aeronautic maintenance, where the numbers of repair crews and spare planes must be sufficiently large to meet the necessary operational capacity. Bayesian guarantees for this to happen can be given using predictive or posterior distributions.     

Risk of Error and the Kappa Coefficient of a Binary Diagnostic Test in the Presence of Partial Verification

The accuracy of a binary diagnostic test is usually measured in terms of its sensitivity and its specificity, or through positive and negative predictive values. Another way to describe the validity of a binary diagnostic test is the risk of error and the kappa coefficient of the risk of error. The risk of error is the average loss that is caused when incorrectly classifying a non-diseased or a diseased patient, and the kappa coefficient of the risk of error is a measure of the agreement between the diagnostic test and the gold standard. In the presence of partial verification of the disease, the disease status of some patients is unknown, and therefore the evaluation of a diagnostic test cannot be carried out through the traditional method. In this paper, we have deduced the maximum likelihood estimators and variances of the risk of error and of the kappa coefficient of the risk of error in the presence of partial verification of the disease. Simulation experiments have been carried out to study the effect of the verification probabilities on the coverage of the confidence interval of the kappa coefficient.     

Rank tests in the two-sample scale problem with unequal and unknown locations

The two-sample scale problem is studied in the case of unequal and unknown location parameters. The method proposed is based on the idea of Moses (1963) and it is distribution-free. The two samples are separated into random subgroups of the same sizek. It is proposed to choosek=4 and to apply the Wilconxon test or the Savage test to the ranges or sample variances of the subgroups. The asymptotic power functions of the tests are compared. For small and moderate sample sizes simulations are carried out. Relations to some other procedures, especially to the method of Compagnone and Denker (1996) are briefly discussed.     

Population policies in advanced societies: Pronatalist and migration strategies

This paper discusses pronatalist and migration policies that have been introduced in selected European countries. Measures and objectives are briefly described before an evaluation of the efficacy of each is provided. The case studies chosen show that pronatalist policies have had limited effects. Migration policies seem to have been more effective, although their aims so far have been largely non-demographic. Migration strategies will increasingly have to be considered for demographic reasons in the future, to counterbalance population decline. Both pronatalist and migration strategies tend to conflict with other policies (social and economic policies, emancipation or housing policies), and to be in competition with the demands of an ageing society. Limits to the development or expansion of either strategy are spelled out. Finally a few untried mechanisms are mentioned.