Introduction

In previous chapters in this book, we introduced the general steps to pursue evidence-based clinical practice¹ and explained how to search for² and critically appraise studies about therapy,³ harm,⁴ diagnosis,⁵ systematic reviews,⁶ and clinical practice guidelines.⁷ In this chapter, we turn to appraising the evidence from a study whose investigators relied on qualitative research.

Qualitative research is an inquiry process that focuses on meaning and interpretation.^8,9 Investigators conducting this type of research aim to explore social or human problems.^8,9 Qualitative researchers often address real-world situations in which complex systems are greater than the sum of their parts.¹⁰ Qualitative researchers not only aim to understand how people think about the world and how they act and behave in it, their study results also can extend beyond patients’ personal experiences to explore interactions and processes within organizations or other environments.¹¹ In the context of evidence-based medicine, the results of qualitative research can be particularly important in helping clinicians to understand patients’ values and preferences.^12,13

When Is Qualitative Research Relevant?

There are numerous reasons for conducting a qualitative study. Qualitative research is relevant when little is known about a topic or to address questions that cannot be answered by quantitative methods. Qualitative research results also can be relevant when a clinician wants to study how potential barriers to care are perceived, to describe a decision-making process, or to examine why interventions work or do not work. Qualitative research results can be influential when examining the kinds of impact (both anticipated and unanticipated) that might be perceived from using different intervention strategies.¹⁴ Qualitative researchers seek in-depth understandings of “what is going on in the world” and also can challenge assumptions about that world and the people who live and interact in it.¹⁵ Investigators of qualitative research studies that are relevant for clinicians address a social phenomenon and seek a theoretical or conceptual understanding of a particular problem.¹⁶ Qualitative researchers in oral health have conducted studies that have addressed issues such as the effect of having natural teeth as a person gets older, dentists’ perceptions and experiences of treating people who receive social assistance, experiences of tooth loss and replacement, and oral health preferences in patients with diabetes.^17–20

Where to Find Qualitative Studies

It can be difficult to identify qualitative studies because their key words often do not map easily to medical subject headings (MeSH) terms, which are used for indexing articles in MEDLINE, and these types of studies are not always published in journals that are indexed in commonly used databases (see Chapter 2). However, in 2003, the National Library of Medicine introduced “qualitative research” as a MeSH term. To make a search more sensitive, a clinician using PubMed can apply filters such as “qualitative” or “interview” in the title or abstract fields or the term “experience” in the text word field.

Critically Appraising Qualitative Research to Inform Clinical Decisions

There are many approaches (also referred to as methodologies or traditions) to conducting qualitative research, including grounded theory, phenomenology, and ethnography. These approaches, in addition to numerous theoretical perspectives, often shape the research question, data collection, data analysis, and choices for promoting rigor in the study. Unlike quantitative research, there is no hierarchy among the approaches in qualitative research; no approach is more likely to get to the “truth” than another.

Over 100 checklists are available to critically appraise a qualitative study.²² Many of these checklists are procedural in nature, focusing on the methods alone and diverting attention away from the analytic content of the work and the substantive findings.²³ In addition, many checklists consider all qualitative research to be the same, as they fail to acknowledge differences between approaches or variants within each of the approaches.²⁴ For the purposes of this chapter, we relied on Giacomini and Cook’s¹⁶ criteria because these authors specifically developed criteria for use in evidence-based practice. According to these criteria, the process of using the results of a qualitative research study to inform clinical decisions involves assessing the credibility, the results, and the applicability of those results. Below, we describe each of these three steps.

Are the Results Credible?

Investigators have defined credibility as the degree of confidence that a clinician could have that a study’s findings represent the “truth.”^25,26 Discussions about and techniques for establishing credibility have evolved over the past 30 years since the term was conceptualized. According to our criteria,¹⁶ answering the following questions can provide key insights into the credibility of the findings of a qualitative study.

Was the Choice of Participants or Observations Explicit and Comprehensive?

One of the hallmarks of qualitative research is purposeful (or purposive) sampling.^10,27–29 Purposeful sampling refers to the process of recruiting information-rich cases (for example, people or documents) that promise to provide a full and sophisticated understanding of the phenomenon.^10,30,31 By selecting information-rich cases, qualitative researchers gain efficiency in learning about the issues of central importance to the research.¹⁰

There are many types of purposeful sampling strategies. These include, but are not limited to, selecting cases that are diverse or heterogeneous as related to dimensions, such as age, that are deemed important to the researchers (maximum variation sampling); selecting a homogeneous sample to describe a particular subgroup in depth (homogenous sampling); using key sources and initial participants to inform the selection of subsequent participants (snowball sampling); and using the categories and theories that are developed during data analysis to inform future sampling (that is, theoretical sampling).^10,29 The researcher’s decision to use any one, or a combination, of these sampling strategies often depends on a variety of elements, including what occurs as data are being collected and analyzed, the type of approach within which the researcher is operating (for example, using the data collected to develop theoretical ideas, concepts, models, and formal theories, which is an approach traditionally referred to as grounded theory³²), and the data collection techniques used (for example, individual interviews, focus groups, or documents). For example, in a qualitative study that explores the perceptions of people who have undergone a particular experience (phenomenological research), the researcher would be sure to choose participants who have undergone the experience of interest (criterion sampling). When qualitative researchers are planning to conduct focus groups, they may prefer homogenous sampling because they want to minimize variation in the sample, such as a power differential among group members.³³ For example, in a study in which the objective was to understand how dentists perceived and experienced treating people who received social assistance,¹⁹ the authors used maximum variation sampling to recruit dentists who had potentially diverse experiences with people living with poverty.

In summary, when assessing whether the researchers’ choice of participants or observations was explicit and comprehensive, clinicians should look for some description of purposeful sampling, even if the researchers did not specifically use the term “purposeful.”

Was Research Ethics Approval Obtained?

Similar to other types of research studies, qualitative research studies typically require research ethics approval. Several ethical issues are considered to be unique to qualitative research. For example, it is important to realize that participants can shape the data and create ethical dilemmas; the communities being researched are not passive components of the research study.³⁴ One ethical issue that occurs during analysis is whether participants should have a say in how the researchers interpret their statements.³⁵ This issue can be especially important to acknowledge if researchers solicit feedback from participants about the study findings (known as “member checking,” “member validation,” or “respondent validation”).³² Strategies for member checking include sending participants their interview transcripts or summaries of the findings. Some researchers view member checking as a criterion of critical appraisal; however, it might instead be viewed as another way of gathering data that has ethical consequences.^32,36

Another ethical consideration of qualitative researchers arises when the openness and intimacy of the research leads participants to disclose information that they may later regret having shared.^35,37 To minimize this risk, qualitative researchers are careful to maintain a professional distance from their participants so that they do not lead participants to believe they have entered into a therapeutic relationship.³⁵ Because of the small sample sizes used in qualitative research, it is important that researchers do not reveal too much information about their study sample (for example, the hospital from which patients were recruited), as there is always the possibility that readers may be able to identify participants.³⁸ Ethical issues such as those described previously are not always captured by standard applications for research ethics board approval, yet qualitative researchers may need to discuss these issues as they carry out their research.

Was Data Collection Sufficiently Comprehensive and Detailed?

Among the numerous techniques for collecting data for a qualitative study, the most common are one-on-one interviews, focus groups, observations, and documents. An interview is an active process in which interviewer and interviewee, through their relationship, produce knowledge or data.^31,35 Focus groups are distinguished from one-onone interviews because of the researcher’s ability in focus group sessions to explore the interactions among research participants.³⁹ Researchers can use observations to study behavior in a natural environment, such as publicly accessible spaces,¹¹ and they can also analyze documents and records. Documents might include public records (for example, government documents, television scripts, minutes of meetings), private documents (for example, letters, medical histories, school records), and photographs.³²

It is appropriate to use a single technique or a combination of techniques for collecting data in qualitative research. For example, in grounded theory studies, researchers may combine focus groups with interviews.^40,41 In an ethnographic study, researchers may combine observations with interviews.⁴² Although using a combination of techniques is not necessary, doing so can allow the researcher to provide an enhanced description of the phenomenon’s structure.⁴⁰

It is helpful when qualitative researchers outline the topic areas they covered in the interview.35 Some journal reviewers like to see the actual interview questions presented in a table. However, individual interview questions or prompts can be revised to adapt to the ongoing data analysis or circumstances in the field.¹¹ In some instances, a researcher conducts a single interview with each participant; in other studies, researchers conduct multiple interviews.

There are no hard-and-fast rules to determine sample size in qualitative research. The aim of data collection is to obtain a rich description of the phenomenon of study rather than to generalize to a population of interest.⁴³ Creswell⁸ proposed sample sizes for different qualitative approaches; however, many researchers use a standard strategy in which they stop collecting data when they believe that further data collection will add little or no important new information relevant to the analysis (a state of affairs referred to as saturation).

In a similar manner to quantitative researchers, qualitative researchers collect some demographic data (for example, age, sex, race, education status) to describe the sample as well as the context or setting from which the sample was drawn. For example, the setting can be a dental practice, a screening program, a school, or the community.

In summary, in assessing whether data collection was comprehensive and detailed, clinicians should look for descriptions of how the qualitative researchers collected the data (for example, interviews or focus groups), what types of data were collected (for example, the topic areas covered, interview guide questions, contextual information such as the setting from which participants were selected), and how the decision to stop collecting data was made by the study team (for example, they concluded that they had reached saturation).

Were the Data Analyzed Appropriately, and Were the Findings Corroborated Adequately?

In quantitative research, researchers generally conduct analysis separate from, and after, data collection to minimize the risk of bias. This is antithetical to what happens in qualitative research. One key feature of qualitative data analysis is that it is iterative, occurring simultaneously with data collection. The design and process of data collection and analysis is circular in nature; analysis unfolds as a researcher generates data and considers theoretical assumptions, a process referred to as emergent analysis.³² As a result, researchers can elaborate on and revise the perspective of the phenomenon being studied as data are collected.³²

Generally, all qualitative analysis involves breaking down data into smaller pieces (that is, coding) and reassembling the pieces to develop an interpretation, a process sometimes referred to as thematic analysis. Themes do not emerge as if they are waiting to be discovered; rather, researchers develop themes on the basis of their interaction with participants and the data collected from participants.44,45 In other words, after accounting for the data, qualitative researchers determine the different paths they can pursue, each of which might be a separate analysis.⁴⁴ Research team members’ input can be especially important at this stage of the research, as are the details related to the qualitative approach or tradition, which may provide further guidance as to how analysis should proceed. For example, a description of classic grounded theory outlines prescriptive steps for analysis.^46,47

The investigators of many qualitative studies stop short of offering an in-depth analysis by providing a list of themes or categories without integrating those themes into a more advanced interpretation.⁴⁴ It is important for qualitative researchers to demonstrate that their analysis extends beyond the initial coding of data. When qualitative researchers report their results, they often provide direct quotations from their interviews to support their claims.²² They also may account for data that do not fit with the themes or concepts or theory developed.⁴⁸ Throughout data collection and analysis, qualitative researchers can enhance credibility for their research by critically self-reflecting on their preferences and theoretical predispositions toward the work (for example, by commenting in field notes and memos), a process referred to as reflexivity.³²

In summary, when assessing whether researchers appropriately analyzed data and corroborated findings, clinicians should determine if the researchers used an iterative process of analysis. In addition, clinicians should look for researchers’ explanations of how they developed and then interpreted concepts, themes, or both.

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