Über die Autorin bzw. den Autor

Nigel Bruce, PhD is Emeritus Professor of Public Health at the Department of Public Health and Policy, University of Liverpool, UK.

Daniel Pope, PhD is Senior Lecturer in Epidemiology and Public Health at the Department of Public Health and Policy, University of Liverpool, UK.

Debbi Stanistreet, PhD is Senior Lecturer and Faculty Director of Widening Participation at the Department of Public Health and Policy, University of Liverpool, UK.

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Quantitative Methods for Health Research

John Wiley & Sons

Chapter One

Introduction and learning objectives

In this chapter, we will begin by looking at different approaches to scientific research, how these have arisen, and the importance of recognising that there is no single, 'right way' to carry out investigations in the health field. We will then go on to explore the research task, discuss what is meant by epidemiology and statistics, and look at how these two disciplines are introduced and developed in the book. The next section introduces the concept of rates for measuring the frequency of disease or characteristics we are interested in, and in particular the terms incidence and prevalence. These definitions and uses of rates are fundamental ideas with which you should be familiar before we look in more detail at research methods and study design. In the final section, we will look at key concepts in disease prevention, including the commonly used terms primary, secondary and tertiary prevention.

The reason for starting with a brief exploration of the nature of scientific methods is to see how historical and social factors have influenced the biomedical and social research traditions that we take for granted today. This will help you understand your own perceptions of, and assumptions about, health research, based on the knowledge and experience you have gained to date. It will also help you understand the scientific approach being taken in this book, and how this both complements, and differs from, that developed in books and courses on qualitative research methods - as and when you may choose to study these. Being able to draw on a range of research traditions and their associated methods is especially important for the discipline of public health, but also for many other aspects of health and health care.

Learning objectives

By the end of Chapter 1, you should be able to do the following:

Briefly describe the philosophical differences between the main approaches to research that are used in the health field.

Describe what is meant by epidemiology, and list the main uses to which epidemiological methods and thought can be put.

Describe what is meant by statistics, and list the main uses to which statistical methods and thought can be put.

Define and calculate rates, prevalence and incidence, and give examples of their use.

Define primary, secondary and tertiary prevention and give examples of each.

1.1 Approaches to scientific research

1.1.1 History and nature of scientific research

Scientific research in health has a long history going back to the classical period. There are threads of continuity, as well as new developments in thinking and techniques, which can be traced from the ancient Greeks, through the fall of the Roman Empire, the Dark Ages and the Renaissance, to the present time. At each stage, science has influenced, and been influenced by, the culture and philosophy of the time. Modern scientific methods reflect these varied historical and social influences. So it is useful to begin this brief exploration of scientific health research by reflecting on our own perceptions of science, and how our own views of the world fit with the various ways in which research can be approached. As you read this chapter you might like to think about the following questions:

What do you understand by the terms science, and scientific research, especially in relation to health?

How has your understanding of research developed?

What type of research philosophy best fits your view of the world, and the problems you are most interested in?

Thinking about the answers to these questions will help you understand what we are trying to achieve in this section, and how this can best support the research interests that you have and are likely to develop in the years to come. The history and philosophy of science is of course a whole subject in its own right, and this is of necessity a very brief introduction.

Scientific reasoning and epidemiology

Health research involves many different scientific disciplines, many of which you will be familiar with from previous training and experience. Here we are focusing principally on epidemiology, which is concerned with the study of the distribution and determinants of disease within and between populations. In epidemiology, as we shall see subsequently, there is an emphasis on empiricism, that is, the study of observable phenomena by scientific methods, detailed observation and accurate measurement. The scientific approach to epidemiological investigation has been described as:

Systematic - there is an agreed system for performing observations and measurement.

Rigorous - the agreed system is followed exactly as prescribed.

Reproducible - all the techniques, apparatus and materials used in making the observations and measurements are written down in enough detail to allow another scientist to reproduce the same process.

Repeatable - scientists often repeat their own observations and measurements several times in order to increase the reliability of the data. If similar results are obtained each time, the researcher can be confident the phenomena have been accurately recorded.

These are characteristics of most epidemiological study designs and will be an important part of the planning and implementation of the research. However, this approach is often taken for granted by many investigators in the health field (including epidemiologists) as the only way to conduct research. Later we will look at some of the criticisms of this approach to scientific research but first we need to look in more detail at the reasoning behind this perspective.

Positivism

The assumptions of contemporary epidemiological investigations are associated with a view of science and knowledge known as positivism. Positivism is a philosophy that developed in the eighteenth century in a period known as the Enlightenment, a time when scientists stopped relying on religion, conjecture and faith to explain phenomena, and instead began to use reason and rational thought. This period saw the emergence of the view that it is only by using scientific thinking and practices that we can reveal the truth about the world (Bilton et al., 2002).

Positivism assumes a stable observable reality that can be measured and observed. So, for positivists, scientific knowledge is proven knowledge, and theories are therefore derived in a systematic, rigorous way from observation and experiment. This approach to studying human life is the same approach that scientists take to study the natural world. Human beings are believed by positivists to exist in causal relationships that can be empirically observed, tested and measured (Bilton et al., 2002), and to behave in accordance with various laws. As this reality exists whether we look for it or not, it is the role of scientists to reveal its existence, but not to attempt to understand the inner...