An equivalence test for comparing DNA sequences

The practice of sequence alignment is constantly oscillating between the risk of overlooking important structure and that of discovering any arbitrarily defined kind of structure anywhere. On the other hand, the use of a condensed consensus sequence may lead to a substantial loss in valuable information. While adopting a Mahalanobis‐type index we allow for a certain degree of uncertainty in the measurements. This uncertainty may be caused by inaccurate measurements or ambiguity. In this paper, we test the similarity between DNA sequences within the framework of equivalence testing, accounting for both variances and covariances between frequencies of nucleotides. Statistical methods for testing equivalence were first developed in the context of pharmacokinetics and later extended to the field of clinical trials. Nowadays, (bio)equivalence tests seem to be less frequently used outside the drug testing field, including statistical genetics. Copyright © 2005 John Wiley & Sons, Ltd.     

Stellungnahmen zum Fall Andrej H.

Ohne Zusammenfassung     

Implementation of a demographic and contraceptive surveillance system in four counties in north China

This paper details efforts to implement a demographic and contraceptive surveillance system in four counties in North China. These counties are taking part in a large-scale field experiment involving the introduction of new contraceptives, greater choice in the use of contraceptives, and better training of family planning personnel. To evaluate the impact of these changes, a system of detailed, individual-level records are being kept in the 24 townships taking part in the project. We discuss the interaction between data collection and policy implementation - its general forms, its manifestations in modern China, and its relevance for the current project. We describe the system that we are implementing - what the old system looked like, and how we have tried to improve it. We evaluate the system's functioning over three years, based on field observations and preliminary data from one of the project's four counties. We conclude that there has been progress in the timely accumulation of standardized data; but there remains an antinomy whereby, past a point, an emphasis on data quality has the effect of sensitizing those responsible for recording data to the problematic nature of such data, thereby weakening accuracy. Many of the issues encountered in implementing the new system are relevant to the larger issues of (a) correct interpretation of data from China, and (b) creating a reasonable climate for change in the family planning system.     

Musculoskeletal problems in bricklayers as a function of length of employment: The role of secondary selection by low-back pain

Low-back problems that are caused by heavy physical work should increase with the length of employment. In a cross-sectional study 195 bricklayers were interviewed and subjected to a medical examination concerned with complaints and functional impairments of the musculoskeletal systems of different body regions (neck/shoulder, arms/hands, back, hip/legs/feet). Summary variables for complaints and impairments indicated an increase with increasing age. Contrary to expectation, in pairs of bricklayers of the same age, but different length of employment, a general decline of complaints and impairments with longer employment was observed. This finding suggested a healthy worker effect. In a follow-up the turnover rate among 190 of the 195 bricklayers of the original study was determined. Bricklayers who had quit the job had a higher incidence of low-back troubles before leaving than bricklayers who had stayed in the job; the relation between turnover and low-back problems was limited to bricklayers older than about 40 years.     

A decomposition of trends in the nonmarital fertility ratios of blacks and whites in the united states, 1960–1992*

We use a method of standardization and decomposition developed by Das Gupta to update Smith and Cutright’s analysis of demographic factors responsible for increases in the nonmarital fertility ratio (illegitimacy ratio) among blacks and whites in the United States. We create standardized rates for each year between 1960 and 1992, and consistent, exhaustive decompositions of the nonmarital fertility ratio for any interval during this period in terms of four components: (1) the age distribution of women of reproductive age, (2) the proportion of women unmarried at each age, (3) the age-specific birth rates of married women, and (4) the age-specific birth rates of unmarried women. Nonmarital fertility ratios are much higher among blacks than among whites, but both increased monotonically from 1960 to 1992. During the last 10 years, each increased by nearly 10 percentage points. Increases in the proportion of women not married, at all ages, account for the preponderance of the increase in black nonmarital fertility ratios. Increasing rates of unmarried childbearing, however, have played a role during the most recent decade (1983–1992). For whites, from 1960 until 1975, declines in marital fertility were most important in producing increases in the proportion of children born out of wedlock. Since then, these proportions have increased primarily because of increases in unmarried women s birth rates, and secondarily because of declines in the proportion of women who are married. These trends are consistent with arguments that emphasize declining economic incentives to marry and reduced access to, and acceptability of, abortion.     

Has the Chinese family planning policy been successful in changing fertility preferences?

Has China’s strict one-child policy been successful in changing fertility preferences? Using linked data from surveys conducted in four counties of northern China in 1991 and 1994, we compare reproductive behavior against prior fertility preferences and show when and where women change from wanting to not wanting more children. The acceptance of policy-sanctioned family size follows a development gradient and reflects the degree of enforcement. High acceptance occurs in the most urban, industrialized county and in the county with the most rigid family planning policy. Acceptance is weaker among women living in the poorest county and in the county where enforcement is most lenient.     

Medicine and the paradigm of Neo-pragmatism a contribution to medical decision theory

Summary The epistemological paradigm of Systematic Neo-Pragmatism, supported by the author, is closely connected with the (semiotic-) pragmatical notion of model. The latter is expounded, and the models in medicine are characterised on the basis of flow charts and correlation-diagrams of the process of diagnosis. Furthermore, the neo-pragmatic concept of medicine is developed and it is shown how medicine is to be defined as a science of action. Finally, a holistic notion of reality in medicine is presented for which the interaction of subject and object as well as the unity of knowledge and action is important.This article is the revised version of a lecture delivered by the author at a symposium held at the Medizinische Universitätsklinik (university hospital), Cologne, 1 October 1982. The lecture has been published in German in Modelle und Realitäten in der Medizin, ed. R. Gross (Stuttgart-New York: Schattauer, 1983, pp. 7–22). For the present publication, the material has been brought up to date. I wish to thank Professor Gross, the editor of Modelle und Realitäten and the publishing house of Schattauer for their kind permission to reprint translated passages from this volume.