Biomedical Ethics Reviews – serie

In the past decade the body of literature in the area of biomedical ethics has expanded at an astounding rate. Indeed, on every major topic, the literature in this area has mUltiplied, and continues to do so, so rapidly that one can easily fall behind important advances in our thinking about and understanding of the problems of contemporary bioethics. Awareness of this need to keep apace of developments in the area prompted a recent reviewer of our earlier collection Biomedical Ethics and the Law (Plenum, 2nd edition, 1979) to suggest that somebody ought to offer the service of providing a biennial review or update of the literature on the various central topics in bioethics. Thomas Lanigan, of The Humana Press, agreed with this last sug­ gestion and so asked us to edit a series of texts consisting of previously unpublished essays on selected topics, a series that would seek to re­ view and update recent literature on the central topics, while also striv­ ing to advance distinctive solutions to the problems on the topics under discussion. Accordingly, this first collection of previously unpublished essays focuses on the selected topics, and the authors commissioned were charged with addressing the basic problems assigned while also bringing the reader either directly or indirectly up to date on the rele­ vant literature.

The National Science Foundation, The National Institute of Occupational Safety and Health, and the Center for Technology and Humanities at Georgia State University sponsored a two-day national conference on Moral Issues and Public Policy Issues in the Use of the Method of Quantitative Risk Assessment ( QRA) on September 26 and 27, 1985, in Atlanta, Georgia. The purpose of the conference was to promote discussion among practicing risk assessors, senior government health officials extensively involved in the practice of QRA, and moral philosophers familiar with the method. The conference was motivated by the disturbing fact that distinguished scientists ostensibly employing the same method of quantitative risk assessment to the same substances conclude to widely varying and mutually exclusive assessments of safety, depending on which of the various assumptions they employ when using the method. In short, the conference was motivated by widespread concern over the fact that QRA often yields results that are quite controversial and frequently contested by some who, in professedly using the same method, manage to arrive at significantly different estimates of risk.

This is the second volume of Biomedical Ethics Reviews, a series of texts designed to review and update the literature on issues of central importance in bioethics today. Five topics are dis­ cussed in the present volume. Section I, Public Policy andRe­ search with Human Subjects, reviews the history of the moral issues involved in the history of research with human subjects, and confronts most of the major legal and moral problems involving research on human subjects. Questions addressed in this section range from those concerning informed and proxy consent to those dealing with the adequacy of monitoring hu­ man research via institutional review boards (IRBs). Section II deals with a second broad topic in bioethics, The Right to Health Care in a Democratic Society. Here the concern not merely that of determining whether there is a right to is health care, but also, if there is such a right, how it ought best be understood and implemented. To answer questions such as these, we learn that one must distinguish legal from moral rights, assess the merits of various theories of rights, clarify the relationship between rights and duties, and attempt to deter­ mine a just method for the distribution of health care. Advances in medical technology often pose new legal and moral problems for legislators and health care practitioners.

Biomedical Ethics Reviews: 1985 is the third volume in a series of texts designed to review and update the literature on issues of central impor­ tance in bioethics today. Four topics are discussed in the present volume: ( 1) Should citizens of the United States be permitted to buy, sell, and broker human organs? (2) Should sex preselection be legally proscribed? (3) What decision-making procedure should medical per­ sonnel employ in those cases where there is a high degree of uncer­ tainty? (4) What do we mean when we use the terms "health" and "disease"? Each topic constitutes a separate section in our text; intro­ ductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recognizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Biomedical Ethics Reviews • 1987 is the fifth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Three topics are discussed in the present volume: (1) Prescribing Drugs for the Aged and Dying; (2) Animals as a Source of Human Transplant Organs, and (3) The Nurse's Role: Rights and Responsibilities. Each topic constitutes a separate sec­ tion in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recognizing this fact, the authors represented in the present volume have made every effort to minimize the use of techni­ cal jargon. At the same time, we believe the purpose of pro­ viding a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces col­ lected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Biomedical Ethics Reviews is an annual publication designed to review and update the literature on issues of central importance in bioethics today. Ordinarily, more than one topic is discussed in each volume of Biomedical Ethics Reviews. This year, however, we have decided to devote the entire volume of Biomedical Ethics Reviews: 1988 to disussion of one topic, namely, AIDS. The ra­ tionale for this decision should be clear: AIDS is arguably the most serious public health threat facing our nation today, and the char­ acter of the disease is such that it creates special problems for ethicists, philosophers, theologians, educators, jurists, health care professionals, and politicians. Indeed, the questions that AIDS gives rise to are so numerous and complex that no one text could hope to treat them exhaustively. Still, if it is impossible, in anyone text, to deal with all of the perplexing difficulties that AIDS generates, it nevertheless remains true that each addition to the AIDS literature contributes to our collective knowledge, and in so doing, brings us one step closer to resolving at least some of the problems associated with the disease. We believe that the articles included in the present volume of Biomedical Ethics Reviews serve this purpose admirably, and we hope the reader will agree. James M. Humber Robert F. Almeder vii Contributors Ronald Carson • Medical Humanities Institute, University of Texas Medical Branch, Galveston, Texas David J.

Should abnormal fetuses be carried to term just to be used for infant transplant organs? Should physicians sell the drugs they prescribe? Should human death be deemed to occur when one permanently loses consciousness? These questions - burning issues in today's already hot bioethical climate - are the focus of this seventh volume in Humber and Almeder's renowned Biomedical Ethics Reviews series. Interdisciplinary in approach, Biomedical Ethics Reviews 1989 offers insightful, penetrating chapters contributed by leading experts in forefront areas of ethics and medicine. Each topic is briefly summarized in an introductory chapter, followed by a more focused, in-depth analysis of the specific issue, as well as a review of the recent literature. And to ensure that these articles are as accessible and useful to as many readers as possible - whether professional or informed layperson - the authors have made every effort to minimize the use of technical jargon. Biomedical Ethics Reviews 1989 is not only a valuable reference, but also constitutes a real eye-opener for everyone concerned with bioethics today!

Biomedical Ethics Reviews • 1990 is the eighth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Two topics are discussed in the present volume: (1) Should the United States Adopt a National Health Insurance Plan? and (2) Are the NIH Guidelines Adequate for the Care and Protection of Laboratory Animals? Each topic constitutes a separate section in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recog­ nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Bioethics and the Fetus: Medical, Moral, and Legal Issues is the ninth volume in the Biomedical Ethics Reviews series of texts designed to review and update the literature on issues of central importance in bioethics today. All of the essays in this volume examine moral and/or legal problems involving human fetal life; summaries of these essays may be found in the text's Introduction. Bioethics is, by its nature, interdisciplinary in character. Recog- nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is well served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also. James M. Humber Robert F. Almeder vii Contributors Andrea L. Bonnicksen * Department of Political Science, Northern lllinois University, DeKalb, lllinois David W. Drebushenko * Department of Philosophy, Central Michigan University, Mount Pleasant, Michigan Roger B. Dworkin * School of Law, Indiana University, Bloomington, Indiana Mary B.Mahowald * Pritzker School of Medicine, The University of Chicago, Chicago, lllinois Christine Overall * Department of Philosophy, Queens University, Kingston, Ontario, Canada WadeL. Robison* College of Liberal Arts, Rochester Institute of Technology, Rochester, New York Barbara Katz Rothman * Department of Sociology, Baruch College, CUNY, New York, New York Thomas A.

Biomedical Ethics Reviews: 1992 is the tenth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Two topics are discussed in the present volume: (1) Bioethics and the Military, and (2) Compulsory Birth Control. Each topic constitutes a separate section in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recog­ nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is well served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also. James M. Humber Robert F. Almeder vii Contributors Paul Christopher • Department of English and Philosophy Division, US Military Academy, West Point, New York Gerard Elfstrom • Department of Philosophy, Auburn University, Auburn, Alabama Nicholas Fotion • Department of Philosophy, Emory University, Atlanta, Georgia Martin Gunderson • Department of Philosophy, Macalester College, St.

In ALLOCATING HEALTH CARE RESOURCES, leading authorities and researchers expose the basic philosophical, ethical, and economic issues underlying the current health care debate. The contributors wrestle with such complicated issues as whether it is ethical to ration health care, the morality of the worldwide bias against children in allocating health care resources, whether sin taxes can be defended morally, and how to achieve a just health care system. The book also includes an insightful analysis of the Clinton health care reform plan. ALLOCATING HEALTH CARE RESOURCES will be of interest to philosophers, health policy experts, medical ethicists, health professionals, and concerned citizens. It serves to clarify and illuminate the logic and rhetoric of health care reform, and so to help us all achieve a fair and equitable distribution of these precious resources.

Today's news is full of stories about suicide machines, and physician-assisted death. Can physician-assisted death be accepted as a reasonable ethical choice? Or must a patient's pain and suffering be prolonged in order to preserve life, without regard to the quality of that life? A mind-opening new book from Humana Press, Physician-Assisted Death provides seven articles by leading authorities examining the medical, ethical, legal, and philosophical issues involved in physician-assisted death and scrutinizing the principal arguments for and against it. The analysis includes an examination of public opinion polls and surveys of physicians, an exploration of the impact on both society and the physician patient relationship, and a discussion of the relationship between physician-assisted death and the right to privacy as recognized by the Supreme Court and common law. This important book adds new dimensions to America's fascination with the activities of Dr. Jack Kevorkian, and the worldwide interest in physician-assisted death evidenced by its legalization in the Netherlands. This book significantly advances the level of the discussion on this vitally important topic.

In Reproduction, Technology, and Rights, philosophers and ethicists debate the central moral issues and problems raised by today's revolution in reproductive technology. Leading issues discussed include the ethics of paternal obligations to children, the place of in vitro fertilization in the allocation of health care resources, and the ethical implications of such new technologies as blastomere separation and cloning. Also considered are how parents and society should respond to knowledge gained from prenatal testing and whether or not the right to abort should relieve men of the duty to support unwanted children. Reproduction, Technology, and Rights illuminates the moral and ethical choices that our society faces because of advances in reproductive technology and helps to make those decisions better informed.

Renowned philosophers and medical ethicists debate and discuss the profoundly important concepts of disease and health. Christopher Boorse begins with an extensive reexamination of his seminal definition of disease as a value-free scientific concept. In responding to all those who criticized this view, which came to be called naturalism or neutralism, Boorse clarifies and updates his landmark ideas on this crucial question. Other distinguished thinkers analyze, develop, and oftentimes defend competing, nonnaturalistic theories of disease. Their combined thoughts review and update an issue of central importance in bioethics today.

Leading bioethicists and philosophers examine and debate the question of how the health care system should deal with using complimentary and alternative medicines. The distinguished authorities writing here both defend and criticize alternative medicine, with some arguing that the medical system should change substantially in order to accommodate alternative medicine, and others claiming that virtually all alternative treatments are worthless. In the heat of the debate many fundamental issues are raised concerning our health care system, among them the questions of therapeutic effectiveness, media truthfulness, the patient's freedom to choose among treatment options, health insurance coverage, the ability of the current healthcare delivery system to meet patients' needs, and government approval of alternative medicines.

In Human Cloning a panel of distinguished philosophers, medical ethicists, religious thinkers, and social critics tackle the thorny problems raised by the now real possibility of human cloning. In their wide ranging reviews, the distinguished contributors critically examine the major arguments for and against human cloning, probe the implications of such a procedure for society, and critically evaluate the "Report and Recommendations of the National Bioethics Advisory Commission." The debate includes both religious and secular arguments, as well as an outline of the history of the cloning debate and a discussion of human cloning's impact on our sense of self and our beliefs about the meaning of life.

The question of whether there might be a duty to die was first raised by Margaret Battin in 1987 in her ground-breaking essay, "Age Distribution and the Just Distribution of Health Care: Is There a Duty­ to-Die?" In 1997 the issue was reprised when two new articles appeared on the topic written by John Hardwig and the other by former Colorado Governor Richard D. Lamm. Given the renewed interest in the topic, as well as its undeniable importance, Biomedical Ethics Re­ views sought to initiate an in-depth discussion of the issue by soliciting articles and issuing a general call for papers on the topic "Is There a Duty to Die?" The twelve articles in this volume represent the ultimate fruits of those initiatives. The first seven essays in this text are sympathetic to the claim that there is a duty to die. They argue either: (a) that some form of a duty to die exists, or (b) that arguments that might be offered against the existence of such a duty cannot be sustained. By way of contrast, the last five articles in the text are critical of duty-to-die claims: The authors of the first three of these five articles attempt to cast doubt on the existence of a duty to die, and the writers of the last two essays argue that if such a duty did exist, severe problems would arise when­ ever we attempted to implement it.

Well-known ethical, medical, legal, and philosophical thinkers debate the conflicting moral and legal demands for maintaining the privacy of health care records in an age of easy computer access to those records and growing pressure by insurance companies, public health agencies, and employers for personal health care data. Interdisciplinary and enlightening, Privacy and Health Care presents the latest moral and legal thinking for and against greater protection of the privacy of health care information, and advances this important issue to a new level of clarity and decision.

Biomedical Ethics Reviews • 1990 is the eighth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Two topics are discussed in the present volume: (1) Should the United States Adopt a National Health Insurance Plan? and (2) Are the NIH Guidelines Adequate for the Care and Protection of Laboratory Animals? Each topic constitutes a separate section in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recog­ nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also.

In ALLOCATING HEALTH CARE RESOURCES, leading authorities and researchers expose the basic philosophical, ethical, and economic issues underlying the current health care debate. The contributors wrestle with such complicated issues as whether it is ethical to ration health care, the morality of the worldwide bias against children in allocating health care resources, whether sin taxes can be defended morally, and how to achieve a just health care system. The book also includes an insightful analysis of the Clinton health care reform plan.ALLOCATING HEALTH CARE RESOURCES will be of interest to philosophers, health policy experts, medical ethicists, health professionals, and concerned citizens. It serves to clarify and illuminate the logic and rhetoric of health care reform, and so to help us all achieve a fair and equitable distribution of these precious resources.

Bioethics and the Fetus: Medical, Moral, and Legal Issues is the ninth volume in the Biomedical Ethics Reviews series of texts designed to review and update the literature on issues of central importance in bioethics today. All of the essays in this volume examine moral and/or legal problems involving human fetal life; summaries of these essays may be found in the text's Introduction. Bioethics is, by its nature, interdisciplinary in character. Recog- nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is well served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also. James M. Humber Robert F. Almeder vii Contributors Andrea L. Bonnicksen * Department of Political Science, Northern lllinois University, DeKalb, lllinois David W. Drebushenko * Department of Philosophy, Central Michigan University, Mount Pleasant, Michigan Roger B. Dworkin * School of Law, Indiana University, Bloomington, Indiana Mary B.Mahowald * Pritzker School of Medicine, The University of Chicago, Chicago, lllinois Christine Overall * Department of Philosophy, Queens University, Kingston, Ontario, Canada WadeL. Robison* College of Liberal Arts, Rochester Institute of Technology, Rochester, New York Barbara Katz Rothman * Department of Sociology, Baruch College, CUNY, New York, New York Thomas A.

This is the second volume of Biomedical Ethics Reviews, a series of texts designed to review and update the literature on issues of central importance in bioethics today. Five topics are dis­ cussed in the present volume. Section I, Public Policy andRe­ search with Human Subjects, reviews the history of the moral issues involved in the history of research with human subjects, and confronts most of the major legal and moral problems involving research on human subjects. Questions addressed in this section range from those concerning informed and proxy consent to those dealing with the adequacy of monitoring hu­ man research via institutional review boards (IRBs). Section II deals with a second broad topic in bioethics, The Right to Health Care in a Democratic Society. Here the concern not merely that of determining whether there is a right to is health care, but also, if there is such a right, how it ought best be understood and implemented. To answer questions such as these, we learn that one must distinguish legal from moral rights, assess the merits of various theories of rights, clarify the relationship between rights and duties, and attempt to deter­ mine a just method for the distribution of health care. Advances in medical technology often pose new legal and moral problems for legislators and health care practitioners.

In the past decade the body of literature in the area of biomedical ethics has expanded at an astounding rate. Indeed, on every major topic, the literature in this area has mUltiplied, and continues to do so, so rapidly that one can easily fall behind important advances in our thinking about and understanding of the problems of contemporary bioethics. Awareness of this need to keep apace of developments in the area prompted a recent reviewer of our earlier collection Biomedical Ethics and the Law (Plenum, 2nd edition, 1979) to suggest that somebody ought to offer the service of providing a biennial review or update of the literature on the various central topics in bioethics. Thomas Lanigan, of The Humana Press, agreed with this last sug­ gestion and so asked us to edit a series of texts consisting of previously unpublished essays on selected topics, a series that would seek to re­ view and update recent literature on the central topics, while also striv­ ing to advance distinctive solutions to the problems on the topics under discussion. Accordingly, this first collection of previously unpublished essays focuses on the selected topics, and the authors commissioned were charged with addressing the basic problems assigned while also bringing the reader either directly or indirectly up to date on the rele­ vant literature.

Biomedical Ethics Reviews: 1985 is the third volume in a series of texts designed to review and update the literature on issues of central impor­ tance in bioethics today. Four topics are discussed in the present volume: ( 1) Should citizens of the United States be permitted to buy, sell, and broker human organs? (2) Should sex preselection be legally proscribed? (3) What decision-making procedure should medical per­ sonnel employ in those cases where there is a high degree of uncer­ tainty? (4) What do we mean when we use the terms "health" and "disease"? Each topic constitutes a separate section in our text; intro­ ductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recognizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Biomedical Ethics Reviews • 1987 is the fifth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Three topics are discussed in the present volume: (1) Prescribing Drugs for the Aged and Dying; (2) Animals as a Source of Human Transplant Organs, and (3) The Nurse's Role: Rights and Responsibilities. Each topic constitutes a separate sec­ tion in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recognizing this fact, the authors represented in the present volume have made every effort to minimize the use of techni­ cal jargon. At the same time, we believe the purpose of pro­ viding a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces col­ lected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Biomedical Ethics Reviews • 1989 is the seventh volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Three topics are discussed in the present volume: (1) Should Abnormal Fetuses Be Brought to Term for the Sole Purpose of Providing Infant Transplant Organs? (2) Should Physicians Dispense Drugs for Profit? and (3) Should Human Death Be Taken to Occur When Persons Perma­ nently Lose Consciousness? Each topic constitutes a separate section in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recog­ nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is admirably served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also.

Biomedical Ethics Reviews: 1992 is the tenth volume in a series of texts designed to review and update the literature on issues of central importance in bioethics today. Two topics are discussed in the present volume: (1) Bioethics and the Military, and (2) Compulsory Birth Control. Each topic constitutes a separate section in our text; introductory essays briefly summarize the contents of each section. Bioethics is, by its nature, interdisciplinary in character. Recog­ nizing this fact, the authors represented in the present volume have made every effort to minimize the use of technical jargon. At the same time, we believe the purpose of providing a review of the recent literature, as well as of advancing bioethical discussion, is well served by the pieces collected herein. We look forward to the next volume in our series, and very much hope the reader will also. James M. Humber Robert F. Almeder vii Contributors Paul Christopher • Department of English and Philosophy Division, US Military Academy, West Point, New York Gerard Elfstrom • Department of Philosophy, Auburn University, Auburn, Alabama Nicholas Fotion • Department of Philosophy, Emory University, Atlanta, Georgia Martin Gunderson • Department of Philosophy, Macalester College, St.

Biomedical Ethics Reviews is an annual publication designed to review and update the literature on issues of central importance in bioethics today. Ordinarily, more than one topic is discussed in each volume of Biomedical Ethics Reviews. This year, however, we have decided to devote the entire volume of Biomedical Ethics Reviews: 1988 to disussion of one topic, namely, AIDS. The ra­ tionale for this decision should be clear: AIDS is arguably the most serious public health threat facing our nation today, and the char­ acter of the disease is such that it creates special problems for ethicists, philosophers, theologians, educators, jurists, health care professionals, and politicians. Indeed, the questions that AIDS gives rise to are so numerous and complex that no one text could hope to treat them exhaustively. Still, if it is impossible, in anyone text, to deal with all of the perplexing difficulties that AIDS generates, it nevertheless remains true that each addition to the AIDS literature contributes to our collective knowledge, and in so doing, brings us one step closer to resolving at least some of the problems associated with the disease. We believe that the articles included in the present volume of Biomedical Ethics Reviews serve this purpose admirably, and we hope the reader will agree. James M. Humber Robert F. Almeder vii Contributors Ronald Carson • Medical Humanities Institute, University of Texas Medical Branch, Galveston, Texas David J.

The National Science Foundation, The National Institute of Occupational Safety and Health, and the Center for Technology and Humanities at Georgia State University sponsored a two-day national conference on Moral Issues and Public Policy Issues in the Use of the Method of Quantitative Risk Assessment ( QRA) on September 26 and 27, 1985, in Atlanta, Georgia. The purpose of the conference was to promote discussion among practicing risk assessors, senior government health officials extensively involved in the practice of QRA, and moral philosophers familiar with the method. The conference was motivated by the disturbing fact that distinguished scientists ostensibly employing the same method of quantitative risk assessment to the same substances conclude to widely varying and mutually exclusive assessments of safety, depending on which of the various assumptions they employ when using the method. In short, the conference was motivated by widespread concern over the fact that QRA often yields results that are quite controversial and frequently contested by some who, in professedly using the same method, manage to arrive at significantly different estimates of risk.