Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Empirical Approach”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1990

Correcting the literature following fraudulent publication.

To gain a better understanding of the problem of dealing with publications whose integrity is subsequently challenged, experience in a well-documented case of research fraud was reviewed. At the University of California San Diego, a faculty committee evaluated 135 publications of Robert Slutsky, MD, and reported to each of the corresponding 30 journals whether each article was valid, questionable, or fraudulent, requesting publication of the criteria and the conclusions. Journals responded slowly to this request; half required additional letters over a 2-year period to elicit a reply. Of the 13 journals that had only valid articles, 5 printed a statement to that effect. Statements concerning 46 of 60 nonvalid articles were eventually published. Journals' inconsistent identification of published statements made it difficult to retrieve them by electronic searching. Only 7 notices covering 15 articles were found by searching under the Medical Subject Heading "Retraction of Publication"; scanning the entire bibliography retrieved 18 articles with retraction notations. A poll showed that journals rarely have written procedures for responding to allegations of research misconduct; in our experience, journals were reluctant to accept authorized retractions or corrections when coauthors failed to act.

Biomedical Research↗
PubMed1985

Measuring dental students' ethical sensitivity.

This paper describes the development of stimulus materials and scoring procedures to measure an individual's ability to recognize the ethical issues often hidden within the dentist's professional problems. The importance of this ability is discussed as it relates to other abilities thought to be necessary conditions for ethical or moral behavior. Dental students completed the ethical sensitivity test and Rest's test of moral reasoning. The sensitivity test requires transcribing verbal responses to audio dramas, a technique that: (1) elicits sufficient data for making inferences about ethical sensitivity, (2) produces good interjudge agreement and interrater reliability, and (3) measures variability in student performance. Data indicate high internal consistency compared with previous efforts to measure components of sensitivity (e.g., empathy), acceptable test-retest reliability for a subsample. and the distinctiveness of sensitivity and reasoning scores. The results have broad application for the teaching of ethics and suggest new directions for the study of professional socialization.

Dentist-Patient Relations↗
PubMed1985

Teaching ethics in dentistry.

This paper describes a curriculum project designed to help dental students identify, reason about, and adequately resolve ethical problems in their chosen profession. The project involved application of a theoretical approach to the study of ethical development that had not been applied previously in professional education. Tests were designed to measure the abilities defined by the theory and used to evaluate the program and to monitor student progress. To date, studies of student abilities and attitudes clearly indicate that the curriculum is needed. Learning activities, created to promote the abilities, are based on studies of the real-life ethical problems confronting dentists and dental students. A program of research and development has been established to study the influence of this curriculum on the abilities defined, and to link them to clinical performance. Half of the dental schools in the United States have requested these materials. Suggestions are made to professional schools considering expanding the teaching of ethics.

Achievement↗
PubMed1985

Relevance and utility of courses in medical ethics. A survey of physicians' perceptions.

In the last decade the teaching of medical ethics has become almost universal in American medical schools. Its effectiveness is, however, just beginning to be evaluated. A stratified random sample of 3,000 practicing physicians who were graduated between 1974 and 1978 was surveyed to evaluate their perceptions of the utility and relevance of medical ethics teaching. Those who had courses in medical ethics perceived it to be of substantial benefit in confronting the actual ethical issues they encountered in daily practice. They favored the continuation and expansion of the teaching of medical ethics and had suggestions for its improvement. Data were also obtained on the relative frequency of specific ethical issues in practices and on the relative influence of home, personal values, medical education, medical practice, and ethics courses on respondents' approaches to ethical issues.

Attitude of Health Personnel↗
PubMed1993

Evaluating ethics committees: a view from the outside.

More than 60 percent of hospitals have ethics committees. The wide-scale, voluntary adoption of these committees by hospitals is surprising, given the lack of data on their effectiveness. Little effort has been made to evaluate such committees, in part because of the lack of consensus on their purpose. The argument presented here is that, from a policy perspective, the committees' purpose must be to safe-guard patients' interests; a framework for evaluating committees based on that objective is outlined. The criteria for evaluation include access, quality, and cost effectiveness. Existing data used to assess ethics committees, using these criteria. Based on available data, it is questionable whether ethics committees are performing any better or worse than alternative mechanisms to achieve the same goal.

Consensus↗
PubMedDate not supplied

Empirical-Bayes and semi-Bayes approaches to occupational and environmental hazard surveillance.

Empirical-Bayes methods offer potentially dramatic improvements in statistical accuracy over conventional statistical methods. We provide an elementary introduction to empirical-Bayes analysis of occupational and environmental hazard surveillance data. Such analyses are especially well suited to situations in which many associations must be examined, but few or none can be estimated precisely. Statistical issues in hazard surveillance are reviewed, followed by a discussion of the rationale and methods for empirical-Bayes analyses, using a study of occupational exposures and cancer mortality to illustrate key concepts. Finally, the assumptions underlying empirical-Bayes analyses are discussed critically, with special attention to the "exchangeability" assumptions that distinguish empirical-Bayes from conventional methods.

Bayes Theorem↗
PubMed1993

[Empirical estimation of recurrence risk in diseases with variable age-at-onset: correction].

Combinatorial approach in empirical estimation of recurrence risks in variable age-at-onset (AO) was elaborated in [2], where special combinatorial coefficient was introduced, the so called "constrained polynomial coefficient", which permit to count the permutations of AO-sibling classes, constrained by their age to the time of study (ATS). Unfortunately giving account of method of calculation md--the table morbidity rate--for siblings of age d in [2] were not introduced limitations for AO or ATS of those siblings, which were affected before or not yet reached the age d under evaluation. Lack of the limitations result in the estimate of prevalence (i.e. the proportion of affected siblings, with the given AO, among all the siblings), but not incidence or age-specific morbidity rate (i.e. the proportion of the siblings, affected in the d-th age interval among those siblings, who reached and/or outlive the age d, being free of disease before the age d under evaluation). In this communication the oversight is removed and the method of calculation of md is simplified: only the two classes instead of a lot of the possible AO-classes of siblings are considered, namely--"affected in the d-th age interval" and "health in the d-th age interval" under evaluation. Thus, the way of calculation of md may be reduced to the simple binomial case.

Age of Onset↗
PubMedDate not supplied

Safety evaluation of chemical mixtures and combinations of chemical and non-chemical stressors.

Recent developments in hazard identification and risk assessment of chemical mixtures are reviewed. Empirical, descriptive approaches to study and characterize the toxicity of mixtures have dominated during the past two decades, but an increasing number of mechanistic approaches have made their entry into mixture toxicology. A series of empirical studies with simple chemical mixtures in rats is described in some detail because of the important lessons from this work. The development of regulatory guidelines for the toxicological evaluation of chemical mixtures is discussed briefly. Current issues in mixture toxicology include the adverse health effects of ambient air pollution; the application of such modern, sophisticated methodologies as genomics, bioinformatics, and physiologically based pharmacokinetic modeling; and databases for mixture toxicity. Finally, the state of the art of our knowledge on the potential adverse health effects of combined exposures to chemicals and non-chemical stressors (noise, heat/cold, microorganisms, immobilization, restraint, or transportation), research initiatives in these fields, and the development of an indicator for the cumulative health impact of multiple environmental exposures are discussed.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

Analysis of the thermal and pH stability of human respiratory syncytial virus.

Respiratory syncytial virus (RSV) was studied as a function of pH (3-8) and temperature (10-85 degrees C) by fluorescence, circular dichroism, and high-resolution second-derivative absorbance spectroscopies, as well as dynamic light scattering and optical density as a measurement of viral aggregation. The results indicate that the secondary, tertiary, and quaternary structures of RSV are both pH and temperature labile. Derivative ultraviolet absorbance and fluorescence spectroscopy (intrinsic and extrinsic) analyses suggest that the stability of tertiary structure of RSV proteins is maximized near neutral pH. In agreement with these results, the secondary structure of RSV polypeptides seems to be more stable at pH 7-8, as evaluated by circular dichroism spectroscopy. The integrity of the viral particles studied by turbidity and dynamic light scattering also revealed that RSV is more thermally stable near neutral pH and particularly prone to aggregation below pH 6. By combination of the spectroscopic data employing a multidimensional eigenvector phase space approach, an empirical phase diagram for RSV was constructed. The pharmaceutical utility of this approach and the optimal formulation conditions are discussed.

Circular Dichroism↗
PubMedDate not supplied

Last chance therapies and managed care. Pluralism, fair procedures, and legitimacy.

How can health plans make fair determinations about when "experimental" (and costly) treatments such as high dose chemotherapy with autologous bone marrow transplantation should be covered despite lack of clear clinical consensus about their benefits? Different models for managing "last chance" therapies evolving in some health plans offer promising examples of how issues of fairness and legitimacy in decision-making can be addressed.

Antineoplastic Agents↗
PubMed1999

Patient care information systems and health care work: a sociotechnical approach.

Those who face the difficulties of developing useful patient care information systems (PCISs) often stress the importance of 'organizational issues'. Building upon recent sociological insights in the construction and use of information technologies for (health care) work, this paper underscores the importance of these insights for the development and evaluation of these systems. A sociotechnical approach to PCISs in health care is outlined, and two implications of this empirically grounded approach for the practices of developing and evaluating IT applications in health care practices are discussed. First, getting such technologies to work in concrete health care practices appears to be a politically textured process of organizational change, in which users have to be put at center-stage. This requires an iterative approach, in which the distinctions between 'analysis', 'design', 'implementation' and 'evaluation' blur. Second, a sociotechnical approach sheds new light on the potential roles of IT applications in health care practices. It is critical of approaches that denounce the 'messy' and 'ad hoc' nature of health care work, and that attempt to structure this work through the formal, standardized and 'rational' nature of IT systems. Optimal utilization of IT applications, it is argued, is dependent on the meticulous interrelation of the system's functioning with the skilled and pragmatically oriented work of health care professionals.

Information Systems↗
PubMed1989

Patterns of personality consistency and change from childhood through adolescence.

Consistency and change in personality development is typically studied through examination of correlations indexing the consistency of individual differences over time. Despite well-known difficulties which inherently limit this approach, few empirical efforts take advantage of alternative methods. We utilize a "person-centered" approach which permits separate and independent measurement of consistency and change for each person studied. Such measures were obtained covering four intervals between ages 3 and 18 in a longitudinally studied sample. These analyses and subsequent results extend and elaborate earlier results reported in Lives through Time (Block, 1971). It is apparent that there are wide individual differences in the degree of personality consistency and change manifested by subjects, and that the degree and timing of change permit the description of various different developmental trajectories. These pathways are described and compared to results obtained by Block (1971). This research is intended as an illustration of the possibilities obtained through person-centered approaches to the study of personality consistency and change.

Child, Preschool↗
PubMedDate not supplied

The importance of preservation of the ethical principle of equipoise in the design of clinical trials: relative impact of the methodological quality domains on the treatment effect in randomized controlled trials.

Previous research has identified methodological problems in the design and conduct of randomized trials that could, if left unaddressed, lead to biased results. In this report we discuss one such problem, inadequate control intervention, and argue that it can be by far the most important design characteristic of randomized trials in overestimating the effect of new treatments. Current guidelines for the design and reporting of randomized trials, such as the Consolidated Standards of Reporting Trials (CONSORT) statement, do not address the choice of the comparator intervention. We argue that an adequate control intervention can be selected if people designing a trial explicitly take into consideration the ethical principle of equipoise, also known as "the uncertainty principle."

Bias↗
PubMed1999

Individual prior information in a physiological model of 2H8-toluene kinetics: an empirical Bayes estimation strategy.

Physiologically-based toxicokinetic (PBTK) models are widely used to quantify whole-body kinetics of various substances. However, since they attempt to reproduce anatomical structures and physiological events, they have a high number of parameters. Their identification from kinetic data alone is often impossible, and other information about the parameters is needed to render the model identifiable. The most commonly used approach consists of independently measuring, or taking fom literature sources, some of the parameters, fixing them in the kinetic model, and then performing model identification on a reduced number of less certain parameters. This results in a substantial reduction of the degrees of freedom of the model. In this study, we show that this method results in final estimates of the free parameters whose precision is overestimated. We then compared this approach with an empirical Bayes approach, which takes into account not only the mean value, but also the error associated with the independently determined parameters. Blood and breath 2H8-toluene washout curves, obtained in 17 subjects, were analyzed with a previously presented PBTK model suitable for person-specific dosimetry. Model parameters with the greatest effect on predicted levels were alveolar ventilation rate QPC, fat tissue fraction VFC, blood-air partition coefficient Kb, fraction of cardiac output to fat Qa/co and rate of extrahepatic metabolism Vmax-p. Differences in the measured and Bayesian-fitted values of QPC, VFC and Kb were significant (p < 0.05), and the precision of the fitted values Vmax-p and Qa/co went from 11 +/- 5% to 75 +/- 170% (NS) and from 8 +/- 2% to 9 +/- 2% (p < 0.05) respectively. The empirical Bayes approach did not result in less reliable parameter estimates: rather, it pointed out that the precision of parameter estimates can be overly optimistic when other parameters in the model, either directly measured or taken from literature sources, are treated as known without error. In conclusion, an empirical Bayes approach to parameter estimation resulted in a better model fit, different final parameter estimates, and more realistic parameter precisions.

Adult↗