Introduction to Quantitative Research

Introduction to Quantitative Research


What do you think of when you hear the word research? Frequently, the word experiment comes to mind. One might equate experiments with randomizing subjects into groups, collecting data, and conducting statistical analyses. Many people believe that an experiment is conducted to answer a clinical question, such as “Is one pain medicine more effective than another?” These ideas are associated with the classic experimental design originated by Sir Ronald Fisher (1935). Fisher is noted for adding structure and control to the steps of the quantitative research process to decrease the potential for error and improve the accuracy of study findings.

Four types of quantitative research are included in this text: descriptive, correlational, quasi-experimental, and experimental. Fisher’s experimentation provided the groundwork for what is now known as experimental research. Throughout the years, other quantitative approaches have been developed. Campbell and Stanley (1963) are noted for developing quasi-experimental designs for conducting quantitative research. Karl Pearson (Kerlinger & Lee, 2000) developed statistical approaches for examining relationships among variables, which increased the conduct of correlational research. The fields of sociology, education, and psychology are noted for their development and expansion of strategies for conducting descriptive research. The steps of the research process used in these different types of quantitative study are the same, but the philosophy and strategies for implementing these steps vary with the approach.

Many quantitative research approaches and designs are essential to develop the body of knowledge needed for evidence-based practice. Thus, quantitative research is a major focus throughout this textbook. This chapter provides an overview of quantitative research by (1) discussing concepts relevant to quantitative research, (2) identifying the steps of the quantitative research process, and (3) providing examples of different types of quantitative studies.

Concepts Relevant to Quantitative Research

Some concepts relevant to quantitative research are basic research, applied research, rigor, and control. These concepts are defined here, and the major points are reinforced with examples from quantitative studies.

Basic Research

Basic, or pure, research is a scientific investigation that involves the pursuit of “knowledge for knowledge’s sake,” or for the pleasure of learning and finding truth (Nagel, 1961). The purpose of basic research is to generate and refine theory and build constructs; thus, the findings are frequently not directly useful in practice. However, because the findings are more theoretical in nature, they can be generalized to various settings (Wysocki, 1983).

Basic research also examines pathological and physiological responses as well as underlying mechanisms of actions of an intervention or outcome (Fawcett & Garity, 2009). Often basic research is conducted in a laboratory with animals or human tissues. For example, cachexia in cancer patients clinically manifests as anorexia, weight loss, and wasting of skeletal muscles that decrease patients’ functioning and quality of life. Cachexia is a very complex process that has been studied for many years, but the knowledge of the specific causes and progression of this condition is still evolving. Thus, additional basic research is needed to examine the pathology of cancer cachexia with skeletal muscle wasting. For example, Byerley et al. (2010) conducted a basic study to examine the causes of body fat loss early in the development of cancer cachexia in male rats. Their study findings are summarized in the following excerpt:

Byerley and colleagues’ (2010) study demonstrates the importance of genetic research in understanding disease pathology. It provides the basis for further research to isolate and characterize the lipolytic protein causing loss of body fat in animals with cancer. This basic research in animals provides the basis for human research in this area. A major force in genetic research is the National Human Genome Research Institute (NHGRI) (2012), which plans and conducts a broad program of laboratory research to improve our understanding of the human genetic makeup, genetics of diseases, and potential gene therapy. This basic research provides a basis for conducting applied “clinical research to translate genomic and genetic research into a greater understanding of human genetic disease, and to develop better methods for the detection, prevention, and treatment of heritable and genetic disorders” (NHGRI, 2012).

Applied Research

Applied, or practical, research is a scientific investigation conducted to generate knowledge that will directly influence or improve clinical practice. The purpose of applied research is to solve problems, to make decisions, or to predict or control outcomes in real-life practice situations. Because applied research focuses on specific problems, the findings are less generalizable than those from basic research. Applied research is also used to test theory and validate its usefulness in clinical practice. Often, the new knowledge discovered through basic research is examined for usefulness in practice by applied research, making these approaches complementary (Bond & Heitkemper, 1987; NHGRI, 2012).

Artinian et al. (2007) conducted an applied study to determine the effectiveness of a nurse-managed telemonitoring (TM) program on the blood pressure (BP) of urban African Americans. The TM program (1) provided BP equipment for patients to monitor their BPs at home, (2) improved access to care by sending patients’ BP readings via telephone to healthcare agencies, and (3) increased monitoring of the patients’ BPs by a care provider with immediate feedback to the patients. The treatment group received the nurse-managed TM intervention or treatment, and the comparison group received usual care (UC). The TM intervention group had a significant reduction in systolic BP in comparison with the UC group, and diastolic BP was greatly reduced but was not statistically significant from that of the UC group at 12 months. Thus, the TM intervention did have a positive impact on the BPs of African Americans, and additional research is needed to determine whether the intervention has a long-term effect on BPs and improves hypertension control in this population. The findings from this applied study do have implications for practice, because this nurse-managed TM intervention significantly affected BP in a population with a high incidence of hypertension. On the basis of Artinian and colleagues’ (2007; 2004; Artinian, Washington, & Templin, 2001) research and the research of others documenting the importance of home BP monitoring, a scientific statement from the American Heart Association, American Society of Hypertension, and Preventive Cardiovascular Nurses Association recommended the use of and reimbursement for home BP monitoring (Pickering et al., 2008). Artinian was a member of the group making this recommendation about home BP monitoring. For more information about the home BP monitoring recommendation, you can view an article on the American Heart Association (2011) website, at

Many nurse researchers have conducted applied studies to produce findings that directly affect clinical practice. Usually, applied studies focus on developing and testing the effectiveness of nursing interventions in the treatment of patient and family health problems. In addition, most previous federal funding for nursing has been granted for applied research. However, the National Institute of Nursing Research (NINR, 2012) recognizes the importance of basic research to nursing and has made it a funding priority. Basic research is needed to expand our understanding of several pathophysiological variables, such as impaired oxygenation and perfusion, fluid and electrolyte imbalance, altered neurological function, impaired immune system, nutritional disorders, and sleep disturbance. NHGRI (2012) priorities include the identification of the genes responsible for numerous human genetic diseases and the generation of animal models essential for the study of human inherited disorders. Because the future of any profession rests on its research base, both basic and applied studies are needed to develop knowledge for evidence-based practice (EBP) in nursing (Brown, 2009; Melnyk & Fineout-Overholt, 2011).

Rigor in Quantitative Research

Rigor is the striving for excellence in research and involves discipline, scrupulous adherence to detail, and strict accuracy. A rigorous quantitative researcher constantly strives for more precise measurement methods, structured treatments, representative samples, and tightly controlled study designs (Borglin & Richards, 2010; Shadish, Cook, & Campbell, 2002). Characteristics valued in these researchers include critical examination of reasoning and attention to precision.

Logistic reasoning and deductive reasoning are essential to the development of quantitative research. The research process consists of specific steps that are developed with meticulous detail and logically linked together. These steps are critically examined and reexamined for errors and weaknesses in areas such as design, intervention development and implementation, measurement, sampling, statistical analysis, and generalization. Reducing these errors and weaknesses is essential to ensure that the research findings are an accurate reflection of reality and can be generalized. Generalizing research findings involves applying the findings from a particular study sample to a large population of similar individuals (Borglin & Richards, 2010). For example, the findings from the study by Artinian et al. (2007) could be generalized from the African American study participants with hypertension to the larger population of African Americans with hypertension.

Another aspect of rigor is precision, which encompasses accuracy, detail, and order. Precision is evident in the concise statement of the research purpose, the detailed development of the study design, and the formulation of explicit treatment protocols. The most explicit use of precision, however, is evident in the measurement of the study variables (Borglin & Richards, 2010). Measurement involves objectively experiencing the real world through the senses: sight, hearing, touch, taste, and smell. The researcher continually searches for new and more precise ways to measure elements and events of the world (Waltz, Strickland, & Lenz, 2010).

Control in Quantitative Research

Control occurs when the researcher imposes “rules” to decrease the possibility of error and thus increase the probability that the study’s findings are an accurate reflection of reality. The rules used to achieve control are referred to as design. Through control, the researcher can reduce the influence or confounding effect of extraneous variables on the study variables. For example, in a study focused on the effect of relaxation therapy on the perception of incisional pain, the extraneous variables, such as type of surgical incision and the timing, amount, and type of pain medication administered after surgery, would have to be controlled to prevent them from influencing the patient’s perception of pain.

Controlling extraneous variables enables the researcher to identify relationships among the study variables accurately and examine the effects of one variable on another. Researchers can control extraneous variables with sampling criteria by selecting a certain type of subject, such as only those individuals who are having abdominal surgery or those with a certain medical diagnosis. Using a random sampling method also improves the control of extraneous variables and reduces the potential for bias in the study sample. The setting can also be structured to control extraneous variables such as temperature, noise, and interactions with other people. The data collection process can be sequenced to control extraneous variables such as fatigue and discomfort (Borglin & Richards, 2010).

Quantitative research requires varying degrees of control, ranging from minimal control to highly controlled, depending on the type of study (Table 3-1). Descriptive studies are usually conducted with minimal control of the study design, because subjects are examined as they exist in their natural setting, such as home, work, or school. However, the researcher still hopes to achieve the most precise measurement of the research variables as possible. Experimental studies are highly controlled and often conducted on animals in laboratory settings to determine the underlying mechanisms for and effectiveness of a treatment. Some common areas in which control might be enhanced in quantitative research are (1) selection of subjects (sampling), (2) reduction of subject or participant attrition, (3) selection of the research setting, (4) development and implementation of the intervention, (5) measurement of study variables, and (6) subjects’ knowledge of the study (Borglin & Richards, 2010; Forbes, 2009; Shadish et al., 2002). Nurses are being encouraged to develop more powerful, controlled, rigorous quantitative studies (NINR, 2012).

Sampling and Attrition

Sampling is a process of selecting subjects, events, behaviors, or elements for participation in a study. In performing quantitative research, you will use a variety of random and nonrandom sampling methods to obtain study samples. Random sampling methods usually provide a sample that is representative of a population, because each member of the population has a probability greater than zero of being selected for a study. Thus, random or probability sampling methods require greater researcher control and rigor than nonrandom or nonprobability sampling methods. Sample sizes in quantitative studies are usually determined with a power analysis to ensure adequate numbers of study participants throughout the study. Researchers are rigorous in reducing attrition, or loss of study subjects needed to describe variables, examine relationships, and determine the effect of interventions (Aberson, 2010; Thompson, 2002). Chapter 15 provides a detailed discussion of the sampling process and determining sample size for quantitative studies.

Research Settings

There are three common settings for conducting research: natural, partially controlled, and highly controlled. Natural settings are uncontrolled, real-life settings where studies are conducted (Fawcett & Garity, 2009; Kerlinger & Lee, 2000). Descriptive and correlational types of quantitative research are often conducted in natural settings. A partially controlled setting is an environment that the researcher manipulates or modifies in some way. A growing number of quasi-experimental studies are being conducted to test the effectiveness of nursing interventions, and these studies are often conducted in partially controlled settings. For example, hospitals, clinics, or rehabilitation centers might be manipulated in selected ways to control for extraneous variables, such as type of care, medications, and family interactions. Highly controlled settings are artificially constructed environments that are developed for the sole purpose of conducting research. Laboratories, experimental centers, and research units are highly controlled settings often used for the conduct of experimental research. Chapter 15 discusses the process for selecting a setting for the conduct of quantitative research.

Development and Implementation of Study Interventions or Treatments

Quasi-experimental and experimental studies examine the effect of an independent variable or intervention on a dependent variable or outcome. More intervention studies are being conducted in nursing to establish an EBP. Controlling the development and implementation of a study intervention increases the validity of the study design and the credibility of the findings. A study intervention needs to be (1) clearly and precisely developed, (2) consistently implemented, and (3) examined for effectiveness through quality measurement of the dependent variables (Forbes, 2009; Morrison et al., 2009; Santacroce, Maccarelli, & Grey, 2004). The detailed development of a quality intervention and the consistent implementation of this intervention are known as intervention fidelity. Chapter 14 provides detailed directions for the development and implementation of a study intervention. Artinian et al. (2007) provided the following detailed description of the implementation of the nurse-managed TM (telemonitoring) intervention to improve the BPs of African Americans:

“Participants in the TM group received UC [usual care] plus nurse-managed TM. Specially trained registered nurses delivered the intervention. During a prescheduled appointment, the intervention nurse delivered the BP monitor and TM link device (device that links BP monitor to the telephone) to the participant’s home. At the time of the home visit, an intervention nurse taught participants how to self-monitor BP in accordance with The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-VII) guidelines (Chobanian et al., 2003), set up the home TM system, demonstrated the system, had participants practice using the BP monitor, and answered questions. Given the memory in the BP monitor and that all BPs recorded by the monitor were telephonically sent to care providers and the principal investigator, participants received verbal and written reminders that the BP monitor was exclusively for their use.… LifeLink Monitoring, Inc. (Bearsville, NY) provided TM services for this study.… Telemonitoring participants were also asked to telephonically send their BP readings to the intervention nurse and their care providers.… Once the intervention nurses received the BP reports, they telephoned each participant to provide feedback in relation to the target goals and to provide telecounseling about lifestyle modification and medication adherence in accordance with JNC-VII guidelines (Chobanian et al., 2003).” (Artinian et al., 2007, p. 315)

Measurement of Study Variables

When you are conducting a quantitative study, you will attempt to use the most precise instruments available to measure the study variables. Using a variety of quality measurement methods promotes an accurate and comprehensive understanding of the study variables. In addition, researchers want to rigorously control the process for measuring study variables to improve the design validity and quality of the study findings (Waltz et al., 2010). Measurement concepts, process, and strategies are the foci of Chapters 16 and 17.

Nursing studies often include the measurement of biophysical variables, which require precise, accurate physiological measures (Ryan-Wenger, 2010). For example, Artinian et al. (2007) described their precise measurement of the dependent physiological variable, BP, with an accurate, nationally standardized device as follows:

Subjects’ Knowledge of a Study

Subjects’ knowledge of a study could influence their behavior and possibly alter the research outcomes. This possibility threatens the validity or accuracy of the study design. An example of this type of threat to design validity is the Hawthorne effect, which was identified during the classic experiments at the Hawthorne plant of the Western Electric Company during the late 1920s and early 1930s. The employees at this plant exhibited a particular psychological response when they became research participants: They changed their behavior simply because they were subjects in a study, not because of the research treatment. In these studies, the researcher manipulated the working conditions (altered the lighting, decreased work hours, changed payment, and increased rest periods) to examine the effects on worker productivity (Homans, 1965). The subjects in both the treatment group (whose work conditions were changed) and the control group (whose work conditions were not changed) increased their productivity. The subjects seemed to change their behaviors (increase their productivity) solely in response to being part of a study. In the study by Artinian et al. (2007, p. 321), both the treatment and the comparison groups experienced decreases in their BPs, and the researchers indicated “the Hawthorne effect may have been a factor, with participants paying more attention to their BP and hypertension self-care behaviors because they were aware of their participation in the study.”

There are several ways to strengthen a study, decreasing the threats to design validity and selecting the strongest design for the proposed study. Chapter 10 addresses design validity, and Chapter 11 focuses on the process for selecting an appropriate study design. Your understanding of rigor and control provide the basis for the implementation of the steps of the quantitative research process, which are precisely executed in descriptive, correlational, quasi-experimental, and experimental research.

Steps of the Quantitative Research Process

The quantitative research process consists of conceptualizing a research project, planning and implementing that project, and communicating the findings. Figure 3-1 identifies the steps of the quantitative research process and shows the logical flow of this process as each step progressively builds on the previous steps. This research process is also flexible and fluid, with a flow back and forth among the steps as researchers strive to clarify the steps and strengthen the proposed study. This back-and-forth flow among the steps is indicated in the figure by the two-way arrows connecting the steps of the process. Figure 3-1 also contains a feedback arrow, indicating that the research process is cyclical, for each study provides a basis for generating further research in the development of knowledge for EBP.

In this chapter, you are briefly introduced to the steps of the quantitative research process that are presented in detail in Unit Two, The Research Process, and Unit Four, Collecting and Analyzing Data to Determine Research Outcomes for Dissemination. The descriptive correlational study conducted by Gill and Loh (2010), on the relationships of perceived stress, optimism, and health-promoting behaviors in new primiparous mothers, is presented as an example for introducing the steps of the quantitative research process. Quotations from this study appear throughout this section, in shaded boxes, to clarify the steps of the quantitative research process. The bracketed words are inserted in the quotations to clarify the key concepts and steps of the quantitative research process.

Formulating a Research Problem and Purpose

A research problem is an area of concern or phenomenon of interest in which there is a gap in the knowledge base needed for nursing practice. The problem identifies an area of concern or phenomenon of interest for a particular population and often indicates the concepts to be studied. The major sources for nursing research problems include (1) nursing practice, (2) literature review, (3) research priorities for funding agencies and professional organizations, (4) researcher and peer interactions, and (5) theory testing. The research problem usually indicates significance to nursing, background knowledge in the area, and problem statement of what is not known (Fawcett & Garity, 2009). As a researcher, you will use deductive reasoning to generate a research problem from a research topic or a broad problem area of personal interest that is relevant to nursing.

The research purpose is generated from the problem and identifies the specific focus or aim of the study. The focus of the study might be to identify, describe, explain, or predict a solution to a situation. The purpose often indicates the type of study to be conducted (descriptive, correlational, quasi-experimental, or experimental) and usually includes the variables, population, and setting for the study. Chapter 5 provides a background for formulating a research problem and purpose. Gill and Loh (2010) identified the following problem and purpose for their study of new primiparous mothers as follows:


“The transition to motherhood is considered to be one of the most stressful and disruptive life transitions (Chen, Kuo, Chou, & Chen, 2007; Warren, 2005).… Additional competing priorities may include learning the maternal role, experiencing physical changes, and learning how to care for their own needs.… These different roles and priorities may be perceived by the new mother as highly stressful, particularly as many of these stressors occur simultaneously (Warren, 2005).… Specifically, perceived stress can occur when the demands of a particular situation are assessed by the individual as greater than their coping attributes [problem significance].…

“Past research has found that perceived stress may lead a new mother to neglect personal health-promoting behaviors in her effort to balance the competing priorities of being a first-time mother (Chen et al., 2007; Walker, 1989).… Optimism and perceived stress have an inverse relationship (Brissette, Scheier, & Carver, 2002).… Optimistic people cope better with stressful situations and thereby report fewer physical health symptoms [problem background].…

“Perceived stress has been associated with fewer health-promoting behaviors in new primiparous mothers, but less is known about the mechanisms responsible for such effects” [problem statement]. (Gill & Loh, 2010, pp. 348–349)

The research problem is significant and is based on pervious research. The problem statement indicates what is not known and provides a basis for the study purpose. The research purpose clearly indicates that the focus of this study is to describe and examine relationships among the variables optimism, perceived stress, and health-promoting behavior in new first-time mothers.

Review of Relevant Literature

A review of relevant literature is conducted to generate an understanding of what is known about a particular situation, phenomenon, or problem and to identify the knowledge gaps that exist. Relevant literature refers to those sources that are pertinent or highly important in providing the in-depth knowledge needed to study a selected problem and purpose. This background enables researchers to build on the works of others. The concepts and interrelationships of the concepts in the problem usually guide the selection of relevant theories and studies presented in the review of literature. Theories are presented to clarify the definitions of concepts and to develop and refine the study framework.

By reviewing relevant studies, researchers are able to clarify (1) which problems have been investigated, (2) which require further investigation or replication, and (3) which have not been investigated. In addition, the literature review can direct researchers in designing the study and interpreting the outcomes. Chapter 6 provides details for conducting a review of relevant literature. Gill and Loh’s (2010) literature review covered the concepts of perceived stress, optimism, and health practice. They also described theoretical models relevant to these concepts. The following excerpt from the study identifies the headings and key ideas covered by the review of relevant literature:

“Perceived Stress and Health Practices

In a longitudinal study from midpregnancy to 12 months postpartum, American primiparous mothers were found to decline gradually in healthy behaviors after birth, with exercise and stress management behaviors performed least by these women (Patteson & Killien, 2001).… There are also significant health benefits in practicing health-promoting behaviors. For example, exercise has been shown to have a dual effect of promoting weight loss and reducing reported stress in new mothers (Groth & David, 2008).…

Theoretical Models

The transactional model for understanding stress emphasizes that the environmental event (e.g., new motherhood) and the cognitive faculties of the individual are constantly in transaction through the process of appraisal (Lazarus & Folkman, 1984).… According to the transactional model of stress and coping, individuals adopt different coping mechanisms to deal with the perceived stress they encounter.…

There are widespread observations that people with optimism generally tend to use less avoidant and more goal-directed coping mechanisms.… In this study, optimism (i.e., dispositional optimism) refers to a personality variable where individuals believe that good outcomes rather than bad will occur in one’s life (Scheier & Carver, 1992). Optimists tend to have an internal locus of control and believe that events result primarily from their own behaviors and actions.…

Gill and Loh (2010) clearly cover relevant studies related to the concepts of stress, health practices, and optimism in pregnant women and new mothers. They also cover relevant theories that describe the relationships among key concepts. The literature review summarizes what is known in the areas of stress, health practices, and optimism in new mothers and clearly indicates what is not known. The study purpose focuses on what is not known, which is how optimism mediates the relationship between perceived stress and health-promoting behaviors.

Developing a Framework

A framework is the abstract, logical structure of meaning that will guide the development of a study and enable the researcher to link the findings to the body of nursing knowledge. In quantitative research, the framework is often a testable midrange theory that has been developed in nursing or in another discipline, such as psychology, physiology, or sociology (Smith & Liehr, 2008). The framework may also be developed inductively from clinical observations.

The terms related to frameworks are concept, relational statement, theory, and framework model or map. A concept is a term to which abstract meaning is attached. A relational statement or proposition declares that a relationship of some kind exists between or among two or more concepts. A theory consists of an integrated set of defined concepts and propositions that present a view of a phenomenon and can be used to describe, explain, predict, or control the phenomenon. The propositions or relationship statements of the theory, not the theory itself, are tested through research.

A study framework can be expressed as a model or a diagram of the relationships that provide the basis for a study and/or can be presented in narrative format. The steps for developing a framework are described in Chapter 7. The framework for Gill and Loh’s (2010) study is presented in Figure 3-2 and is described in the following quote. The framework model identifies the relationships that are examined in this study, and the description of the framework identifies the proposition that was tested by this study.

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Feb 17, 2017 | Posted by in NURSING | Comments Off on Introduction to Quantitative Research

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