Qualitative and quantitative methods in health: definitions, differences and research subjects



Egberto Ribeiro Turato

Laboratório de Pesquisa Clínico-Qualitativa. Faculdade de Ciências Médicas. Universidade Estadual de Campinas. Campinas, SP, Brasil





The interest and accomplishments in qualitative research have been increasing in health. As a consequence, there is a greater demand for both institutional research programs and scientific journal publications. This article has the following purposes: (a) to present some definitions in qualitative methods used in Humanities and Health; (b) to compare them to the usual quantitative methods of health sciences; and, finally, (c) to illustrate the subject with the most important constructs in these methodological fields. Above all, the author's scope was to provide criteria to evaluate the pertinence of the path taken by qualitative researchers, from research plan elaboration to result interpretation.

Keywords: Biomedical research, methods. Qualitative research. Research personnel.




There have been increasing interest and accomplishments in qualitative research in the health field. There is thus greater demand by researchers for institutional research programs as well as academic meetings and scientific journals in order to carry out projects and disseminate their work results. In the last decade, qualitative research has become well accepted by medical journals. But, in earlier times, qualitative research manuscripts had been rejected for being considered nonscientific, as if they consisted of merely curious personal accounts of one's life events without systematic concerns, i.e., they were deemed anecdotal.2

Fortunately nowadays many scientific journals generally publish qualitative research studies. For example, the Journal of Public Health (Revista de Saúde Pública), a renowned periodical, has even guidelines for evaluating qualitative papers by its referees. It is now common to find health professionals who not only give importance to qualitative methods in medicine but also recognize their help for better understanding patients' life. An increasing number of medical researchers have been using these methods in their work.2 However, it does not necessarily mean that qualitative methods are well understood and properly used as, among other problems, some investigators present qualitative study reports with common sense conclusions.

Facing these challenges, there was a need for a tutorial article discussing qualitative research methodology, bringing to the readers its most relevant definitions. In addition, such definitions would need to be compared with both classic concepts of conventional field research, such as epidemiological research, and other procedures of scientific surveys generally constructed with measurements and other mathematical tools. And finally, the academic audience could discriminate better the themes and constructs which are currently most explored in these methodological fields.

The specific objective of this paper is to provide input for exercising good judgment and further exploring the issue of qualitative methods with a well-delimited object to be employed in understanding the health-illness setting/process. Readers and consumers of these scientific outputs are here targeted to allow them to have a greater clarity of criteria to critically evaluate the pertinence of the path taken by qualitative researchers, from research plan elaboration and data collection to result interpretation. Similarly, this article purpose is to provide information to those academics who intend to develop qualitative research projects, to allow them to apply the same accuracy as expected for any generating knowledge in science. Hence, it is presented the concerning definitions and a comparative discussion between qualitative and quantitative methods and, by the end, a diversified list of conceptual constructions specific to each method vocabulary.



The discourses of Natural Sciences – Physics, Chemistry, Biology and their numerous related sciences, among them Medical Sciences – are associated with the understanding of quantitative or explanatory methods. In the same way, the discussion on Human and Culture Sciences is combined with that on qualitative or understanding methods. Modern scientific thought, as it is known, has started almost four centuries ago with Galileo. It is his legacy of giving autonomy to Science, distinguishing it from both Philosophy and Religion, so delimiting which will be its object, objective and method (observation, experimentation and induction).8 Science has been established since then on the specific object of nature beings, i.e., on the study of the laws that enunciate the links of natural phenomena among themselves, while Philosophy should be concerned with ontological issues (the being as such) and, at last, Religion would preserve, as its object, the so-called religious truths.

Qualitative or understanding methods have a more recent history. They are about a century old and have started at the time of the first ideas of giving autonomy to Human Sciences, arising in counterpoint to the already existing Natural Sciences. From its qualitative methods, the discipline of Anthropology has developed the so-called ethnography, which has been revolutionized in 1920s with Malinowski's publications.10 The anthropologist Malinowski has spent years living among Oceania's natives, participantly observing their lives. From that, Science's history has attributed him the pioneerism in the qualitative scientific methodology, as he systematically described how he had obtained his data and his field experience.

However, credit should be given first to Marx and Freud for having offered important epistemological cuts for new and thorough understanding of the human being, which has initiated autonomous scientific studies in human sciences. These thinkers have built up schools of thought, unveiling the mechanisms of the acting Ideology in social groups and unmasking the mechanisms of the acting Unconscious in individuals' life.4 They have significantly contributed to support the scientificity of Human Sciences, where lies the locus of methodological construction of qualitative research.



From a methodological perspective, if one wants to scientifically explain, for instance, the phenomena related to drug addiction, this is a subject for researchers in psychiatry, epidemiology or clinical pharmacology. But if one wants to understand what substance dependence means in the life of an addicted patient, then it is a subject for qualitative researchers, who can be psychologists, psychoanalysts, sociologists, anthropologists or educators. However, it would be very interesting if health professionals could actually employ qualitative methods. They have the advantage of, due to their clinical practice, having inherent clinical and existential attitude,14 which will allow them to perform rich data collections and to make authoritative result interpretations.

On the other hand, it is crucial to bear in mind a clear concept of research qualitative method to avoid purely reproducing the understanding accrued from other approaches and assertions such as research methods where tools like numbers, percentage calculations, statistical techniques, tables, statistically representative samples, random essays, closed questionnaires or evaluation scales are not employed. To define a concept by denying it does not evidently constitute a definition.14 It is also not the case of saying, as often is intuitively assumed, that qualitative methods are for studying the "quality" of an object. Qualitative methods applied to health employ the concepts borrowed from human sciences, according to which the study focus is not the "thing" itself, but to understand its individual or collective meaning in people's life. It is indispensable to know what the phenomena of both and life generally mean to them, because the meaning has a structuring function: people will organize their lives around what things mean to them, including their healthcare.

It should not, however, be confounded qualitative research in both Health and Human Sciences and the usual research in Nature Sciences. There, qualitative studies are conducted to know the physical, chemical and biological "qualities" of the investigation object. Nature Sciences researchers often refer to the application of qualitative methods while conducting studies, for example, in biology areas, specifically in medical parasitology, with the objective of detecting the presence of protozoans in collected material for clinical testing. It is used the term qualitative, evidently with a specific meaning within its epistemological-methodological model. For that, the researcher will employ techniques such as sample collection according to well-defined procedures; storage in adequate containers, careful sample identification and sample analysis in a well-equipped laboratory. In short, the researcher will study in-depth a particular natural phenomenon and describe its properties, carrying out a qualitative research in Natural Sciences.

Back to the Human and Health Sciences context, it is first presented here a generic definition of qualitative methods by the sociologists Denzin & Lincoln,6 usually quoted in the literature: "Qualitative researchers study things in their natural setting, attempting to make sense of, or interpret, phenomena in terms of the meanings people bring to them". Reading only this definition cannot be enough for an accurate understanding by readers not familiarized with this research approach. It is again underlined that researchers' are not directly interested in studying the phenomenon itself, but their actual target is the meaning the phenomenon have for those experiencing it.

Similarly, the educators Bogdan & Biklen1 point out that "qualitative researchers' goal is to better understand human behavior and experience. They seek to grasp the processes by which people construct meanings and to describe what those meanings are". These authors also assume meaning as the key concept. It is inferred that qualitative researchers does not want to explain events in peoples' life, individually or collectively, by listing and measuring their behaviors or quantitatively correlating their life events. Conversely, their intention is to gain an in-depth knowledge of people's life experiences and their representations of these experiences.

In their attempt to provide a detailed definition on qualitative methods, the nurses Morse & Field12 characterize them as "inductive, holistic, emic, subjective, and process-oriented research methods used to understand, interpret, describe, and develop theory pertaining to a phenomenon or a setting". Although these authors aimed at a comprehensive definition, they left out the terms meaning/signification. In its broad scope, however, the word theory gains strength, which implies that qualitative method is not only a research approach that meets specific demands, but it has the common purpose of creating a model for in-depth understanding of the links among elements, i.e., of exploring an order that is invisible in the ordinary examination. It is also underlined the term process, particularly powerful here, which characterizes the qualitative method as designed to understand how the study object happens or develops; and not to aim at the product, that is, mathematically estimated results. The inductive reasoning relates to the fact that these researchers would ground their work on field data, further exploring individualities and collecting information that would gradually help to build up a plausible and dense theory. Emic means that scientists' interpretations should be made from the interviewees' perspective and should not be a discussion from the researcher's or the literature's view. Original knowledge should be gained and they should not focus on corroborating the already existing theories as this does not contribute to science advancement.

Favoring a structural definition from a sociological perspective, Minayo11 identify qualitative research methodologies as "[…] those capable of incorporating both the meaning and intentionality as inherent to acts, relationships and social structures, the latter considered to be both on their advent and their transformation as significative human constructions". The term meaning gains relevance in the social context in trying to understand the "want to say" regarding to these structures for the study subjects.

Finally, it is presented here the clinical-qualitative methodology definition, a particularization and refinement of the generic qualitative methodologies from Human Sciences, but addressed specifically to the life experience in health settings: "It is the theoretical study – and its corresponding use in investigation – of a set of scientific methods, techniques and procedures, adequate to both describe and interpret the senses and the meanings given to the phenomena and also related to individuals' life (patients or any other participating person in the healthcare setting, such as family members, health professionals and community people).13 In this particular approach, researchers use an eclectic theoretical reference framework for both project writing and result discussion from a interdisciplinary view. The whole scientific undertaking must be supported by three pillars, which work as delimiting characteristics and consist of the following attitudes: existentialist, clinic and psychoanalytic. They provide, respectively, a welcome attitude to human being's inherent angst and anxieties; a proper approach of those who already work with therapeutic aid; and the listening and the valuing of mobilized psychodynamic aspects, overall in their affective and direct relationship with the study subjects. This method has proved to be adequate for qualitative research already carried out in the health area.3,5,7



First, the researcher's interest turns toward the search for the meaning of things because it has an organizing role in human beings. What "things" (phenomena, manifestations, occurrences, facts, events, life experiences, ideas, feelings, subjects) represent shape people's lives. At another level, the meanings "things" acquire are culturally shared and so organize the social group around these representations and symbolisms. In health settings in particular, knowing the meanings of phenomena of the health-disease process is essential for the following: to improve the quality of professional-patient relationship; to promote better adherence of patients and general population to individually administered treatments and collectively implemented preventive measures; to better understand certain feelings, ideas and behaviors of patients as well as their family members and even health professionals.

Second, in this approach, the subjects' natural setting is unequivocally the field, where observation, without variable control, takes place. Third, researchers are themselves a research instrument as they use their sensory organs to grasp the study objects, mirroring them in their consciousness, where they then are converted into phenomenological representations to be interpreted. Fourth, this method has greater data validity strength since the thorough accurate observation and in-depth interview listening of subjects are likely to lead researchers very close to the essence of the study issue. Fifth, since generalization does not derive from (mathematically) estimated results because it is not based on either the quantification of occurrences or the establishment of cause/effect relationships; it becomes possible from the review of initial hypotheses, i.e., the constructed concepts and the original knowledge produced. It is up to research readers/consumers to use them to examine their plausibility and utility in order to understand new cases and settings.

For instructive purposes, it is now relevant to draw the comparative profiles between the characteristics of both qualitative and quantitative methodologies applied to health. Table 1 illustrates the conceptual levels of both methodologies. First it shows the scientific attitude one should adopt when using either one of these methods. It can also be seen the strengths (reliability versus validity) as well as the actual limits of the subject under study in each approach; and then the dissimilarities in the different study designs and research instruments are identified. The critical point is to show the differences in sampling technique and subject sample profile. Data analysis shows distinctive refining of collected data in both methods. Finally, it should be made clear what in fact the conclusions are in each method and the resulting work of disentangling the knots concerning the intended and the possible generalization from both quantitative and qualitative research.

This important chart displaying their dissimilarities reveal that each method has its own identity from the moment the authors formulate the questions (the working hypotheses) up to the writing of their research final reports. The complexity of each scientific undertaking and, most of all, the autonomous epistemological constructions, which give them support, disavow most research studies self-entitled "quanti-quali" to continue to be carried out in the academic environment using this supposedly mixed model. In fact, many such research studies are conceived only on quantitative constructions, since simply embedding subjects' quotations, collected using previously standardized questionnaires, does not acceptably configure a claimed simultaneity of qualitative research.

In conclusion, Tables 2 and 3 aim at codifying the most common used constructs in qualitative and quantitative research, respectively. In the right column, showing how each concept is constituted, well-established definitions from epidemiology literature9 and/or well typified health sciences descriptors15 are presented. It is hoped that a broad and comparative appreciation of the two frames would allow readers to distinguish the investigation health fields for each method



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7. Fontanella BJB, Turato ER. [Doctor-patient relationship barriers to substance dependents seeking treatment]. Rev Saúde Pública 2002;36:439-47.        

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11. Minayo MCS. O desafio do conhecimento: pesquisa qualitativa em saúde. 8ª ed. São Paulo: Hucitec/ Rio de Janeiro: Abrasco; 2004.        

12. Morse JM, Field PA. Qualitative research methods for health professionals. 2nd ed. Thousand Oaks, Sage; 1995.        

13. Turato ER. [Introduction to the clinical-qualitative research methodology: definition and main characteristics]. Rev Portug Psicossomática [Portug J Psychosomatics] 2000;2(1):93-108.        

14. Turato ER. Tratado da metodologia da pesquisa clínico-qualitativa: construção teórico-epistemológica, discussão comparada e aplicação nas áreas da saúde e humanas. 2ª ed. Petrópolis: Vozes; 2003.        

15. U.S. National Library of Medicine. Medical Subject Headings. Available from URL: http://www.nlm.nih.gov/mesh/2005/MBrowser.html [2004 Nov 10]        



Correspondence to
Egberto Ribeiro Turato
Rua Carlos Guimarães, 230 Apto 82
13024-200 Campinas, SP, Brasil
E-mail: erturato@uol.com.br

Received on 24/11/2004. Approved on 5/4/2005.

Faculdade de Saúde Pública da Universidade de São Paulo São Paulo - SP - Brazil
E-mail: revsp@org.usp.br