Nursing Research: Problem Identification and Statement Development
A comprehensive guide for nursing students and practitioners
Introduction to Research in Nursing
Research in nursing is a systematic process that validates and refines existing knowledge while generating new knowledge that directly and indirectly influences clinical nursing practice. The research process begins with identifying a problem area that requires investigation—a critical first step that determines the direction and significance of the entire study.
Clinical Pearl
Evidence-based nursing practice integrates the best available research evidence with clinical expertise and patient values. The quality of nursing research directly impacts patient outcomes, making proper problem identification and statement formulation essential skills for advanced practice nurses.
Identification of Problem Area
The identification of a research problem area is the foundation of the research process. It involves recognizing gaps in knowledge or practice that require investigation to improve patient care and nursing practice.
Sources of Research Problems
Clinical Practice
- Unexpected patient outcomes
- Recurring clinical issues
- Variations in care delivery
- Quality improvement needs
- Workflow inefficiencies
Literature Review
- Gaps in existing research
- Conflicting evidence
- Recommendations for future research
- Outdated clinical guidelines
- Emerging healthcare trends
Societal Needs
- Changing demographics
- Health disparities
- Public health priorities
- Emerging diseases or health threats
- Policy implications
Professional Experience
- Clinical observations
- Theoretical curiosity
- Educational needs
- Administrative challenges
- Interdisciplinary collaboration
Key Concept
Meaningful nursing research problems are derived from significant practice issues that impact patient outcomes, nursing practice, or healthcare delivery systems. The value of research is directly proportional to its relevance to real-world clinical situations.
Steps in Problem Area Identification
Observe Clinical Practice
Identify recurring issues, challenges, or phenomena that affect nursing care or patient outcomes. Consider areas where practice varies or where outcomes are unpredictable or suboptimal.
Conduct Preliminary Literature Review
Examine current research, systematic reviews, and meta-analyses to identify what is known about the topic and where knowledge gaps exist. Look for “recommendations for future research” sections in published studies.
Consult with Colleagues and Experts
Discuss potential research areas with clinical experts, research mentors, and interdisciplinary colleagues to gain diverse perspectives on the significance and feasibility of investigating specific problems.
Consider Organizational Priorities
Align research interests with institutional goals, quality improvement initiatives, or strategic priorities to increase relevance and potential for implementation of findings.
Narrow the Focus
Refine broad areas of interest into specific, manageable research problems that can be investigated with available resources and within reasonable timeframes.
Common Pitfalls in Problem Identification
- Excessive breadth: Choosing problems too broad to be adequately addressed in a single study
- Limited significance: Selecting problems with minimal impact on nursing practice or patient outcomes
- Resource constraints: Identifying problems that require resources beyond what’s available
- Ethical concerns: Choosing problems that pose ethical challenges in research design
- Methodological limitations: Selecting problems that cannot be investigated with robust methodological approaches
Problem Statement
A problem statement is a clear, concise, and specific articulation of the research problem. It serves as the foundation for developing research questions, hypotheses, and the overall research design.
Components of an Effective Problem Statement
| Component | Description | Example |
|---|---|---|
| Problem Background | Brief context explaining the issue’s importance and relevance | “Despite standardized protocols, central line-associated bloodstream infections (CLABSI) continue to occur in critical care units…” |
| Gap in Knowledge | What is currently unknown or unclear about the problem | “…however, little is known about how adherence to protocols varies during different shift times and staffing patterns…” |
| Study Population | The specific group to be studied | “…among registered nurses working in adult intensive care units…” |
| Variables of Interest | Key concepts or phenomena to be examined | “…regarding protocol adherence behaviors, knowledge levels, perceived barriers, and CLABSI rates…” |
| Implications | Potential significance of addressing the problem | “…which could inform targeted interventions to reduce infection rates and improve patient outcomes.” |
Formulating the Problem Statement
The PICOT Framework
The PICOT framework is a structured approach to developing clinical research questions and problem statements:
PICOT Mnemonic
- P – Population/Patient: Who is the target patient group?
- I – Intervention/Issue: What is the intervention or issue being studied?
- C – Comparison: What is the alternative to compare with? (if applicable)
- O – Outcome: What outcomes or results are expected or of interest?
- T – Time: What is the timeframe for the intervention or observation?
Example Problem Statement Using PICOT:
“Among adult patients with type 2 diabetes in primary care settings (P), how does the implementation of a nurse-led telehealth monitoring program (I) compared to standard office-based follow-up care (C) affect glycemic control, medication adherence, and patient satisfaction (O) over a six-month period (T)?”
Types of Problem Statements
Descriptive Problem Statement
Purpose: To describe characteristics, prevalence, or experiences
“This study aims to describe the lived experiences of pediatric oncology nurses who provide end-of-life care and identify coping mechanisms they employ to manage compassion fatigue.”
Correlational Problem Statement
Purpose: To examine relationships between variables
“This study will investigate the relationship between nurse-to-patient ratios in medical-surgical units and the incidence of medication administration errors across three hospital settings.”
Quasi-experimental Problem Statement
Purpose: To test interventions without randomization
“This study will evaluate whether implementing a standardized handoff protocol improves communication accuracy and reduces adverse events in transitioning patients from the emergency department to intensive care units.”
Experimental Problem Statement
Purpose: To determine cause-effect relationships
“This randomized controlled trial will determine if a structured progressive mobility protocol, compared to standard care, reduces length of stay and improves functional outcomes in mechanically ventilated patients.”
Clinical Pearl
The problem statement should be specific enough to guide research design decisions but broad enough to acknowledge the complexity of nursing phenomena. Use active voice and precise language to enhance clarity and strengthen the statement’s impact.
Criteria of Good Research
Good nursing research meets specific criteria that ensure its scientific rigor, ethical soundness, and practical relevance. These criteria should be considered during problem identification and throughout the research process.
Scientific Merit Criteria
Significance
Research addresses an important problem or question that has the potential to advance nursing knowledge, improve patient care, or influence healthcare policy.
Validity
Study design and methods are appropriate for answering the research question. Internal validity (accuracy of conclusions) and external validity (generalizability) are addressed.
Reliability
Research measures and procedures produce consistent results when repeated under similar conditions, enhancing confidence in the findings.
Methodological Quality Criteria
| Criterion | Description |
|---|---|
| Appropriateness of Design | Research design aligns with the research question and problem statement. The selected approach (quantitative, qualitative, or mixed methods) is suitable for addressing the research problem. |
| Sampling Strategy | Sampling method is appropriate for the research design and questions. Sample size is adequate for statistical analysis or theoretical saturation. Selection criteria are clearly defined and justified. |
| Data Collection Methods | Instruments and procedures for data collection are appropriate, valid, and reliable. Data collection processes are systematic and minimize bias. |
| Analytical Rigor | Data analysis techniques are appropriate for the research design and type of data. Statistical methods or qualitative analysis approaches are correctly applied and interpreted. |
| Transparency | Research procedures, decisions, and limitations are clearly documented and reported. Sufficient detail is provided to allow for replication or critique. |
Ethical Standards
Protection of Human Subjects
- Informed consent processes are robust
- Risks to participants are minimized
- Benefits justify any potential risks
- Selection of subjects is equitable
- Privacy and confidentiality are maintained
Research Integrity
- Honesty in reporting results
- Transparency about conflicts of interest
- Appropriate attribution of ideas and contributions
- Avoidance of research misconduct (fabrication, falsification)
- Responsible data management practices
Critical Ethical Considerations
Research involving vulnerable populations (children, pregnant women, cognitively impaired individuals, prisoners) requires additional protections and safeguards. Institutional Review Board (IRB) approval must be obtained before initiating research with human subjects.
Consider cultural sensitivity and respect for diverse populations when designing research and interpreting findings. Acknowledge power differentials between researchers and participants, especially in clinical settings where patients may feel obligated to participate.
Practical Relevance Criteria
Key Concept: The 3 A’s of Relevant Research
Applicability
Research can be translated into nursing practice, education, or administration
Accessibility
Findings are communicated clearly and made available to relevant stakeholders
Actionability
Results provide clear direction for practice changes or future research
Evaluating Research Quality
Critical Appraisal Questions
Problem Identification:
- Is the problem clearly stated and significant to nursing?
- Is the problem narrow enough to be manageable but broad enough to be meaningful?
- Does the problem statement identify the population, variables, and context?
Theoretical Framework:
- Is the research grounded in relevant theory or conceptual models?
- Are key concepts defined conceptually and operationally?
- Is the relationship between the problem and existing knowledge clear?
Methodology:
- Is the design appropriate for the research question?
- Are sampling procedures clearly described and justified?
- Are data collection methods reliable and valid?
- Are analysis procedures appropriate and thoroughly explained?
Results and Conclusions:
- Are findings presented clearly and objectively?
- Do conclusions follow logically from results?
- Are limitations acknowledged and discussed?
- Are implications for practice, theory, or future research addressed?
Clinical Pearl
When evaluating nursing research, consider both methodological quality and clinical applicability. The most rigorous study may have limited value if findings cannot be translated to real-world practice settings. Likewise, practically relevant research must still meet standards of scientific merit to be trustworthy.
Integrating Problem Identification into the Research Process
Problem identification is not an isolated step but an integral part of the research process that influences all subsequent phases. Understanding how problem identification connects to other research elements ensures conceptual clarity and methodological coherence.
The Research Process Continuum
| Research Phase | Relationship to Problem Identification |
|---|---|
| Literature Review | Refines the problem by identifying what is known, what gaps exist, and how others have approached similar problems |
| Theoretical Framework | Provides conceptual structure for understanding the problem and relationships among variables |
| Research Question/Hypothesis | Derives directly from the problem statement, specifying exactly what will be examined |
| Methodology | Selected based on the nature of the problem and research questions |
| Results and Analysis | Interpreted in relation to the original problem to determine if/how it has been addressed |
| Conclusion and Implications | Connect findings back to the original problem, indicating how knowledge has advanced |
FINER Criteria for Research Problems
When evaluating potential research problems, apply the FINER criteria to ensure quality:
- F – Feasible: Adequate subjects, technical expertise, time, and resources available
- I – Interesting: The researcher maintains interest and motivation throughout the study
- N – Novel: Confirms, refutes, or extends previous findings or applies new perspectives
- E – Ethical: Conforms to ethical standards and principles for research
- R – Relevant: To scientific knowledge, clinical practice, policy, or future research
Summary and Key Points
Key Takeaways
- Problem identification is the foundational step in nursing research that determines the direction and significance of investigation.
- A well-formulated problem statement is clear, concise, and specific, outlining the background, knowledge gap, population, variables, and implications.
- The PICOT framework provides structure for developing clinical research questions that address population, intervention, comparison, outcomes, and time.
- Good research meets criteria for scientific merit, methodological quality, ethical soundness, and practical relevance.
- Critical appraisal of research quality involves evaluating problem identification, theoretical framework, methodology, and conclusions.
- Problem identification influences all phases of the research process, from literature review to conclusion and implications.
References
Nursing Research: Writing Objectives and Hypotheses
A Comprehensive Guide for Nursing Students
By Prof. Dr. Elizabeth Montgomery, PhD, RN
Department of Nursing Research | 20 Years of Teaching Experience
1. Introduction: The Foundation of Research
Research objectives and hypotheses form the backbone of any nursing study. They provide direction, focus, and purpose to your investigation, determining what methodology you’ll use, what data you’ll collect, and how you’ll analyze your findings.
Key Concept: Research objectives and hypotheses are not merely formal requirements—they are your research roadmap. Clear objectives and well-formulated hypotheses distinguish a systematic scientific inquiry from a casual investigation.
In nursing research, where our studies directly impact patient care and clinical practice, precision in these elements is not just academically important—it’s ethically essential.
2. Research Objectives: Your Study’s Compass
2.1 Definition and Purpose
Research objectives are clear, concise statements that define what the researcher intends to accomplish through the study. They transform the general purpose of research into specific, measurable goals.
Clinical Pearl: When I review research proposals from clinical nurses, I often find objectives that are too broad. Remember that narrower, more precise objectives lead to more actionable findings that you can implement in practice.
2.2 Types of Research Objectives
| Type | Description | Example in Nursing Research |
|---|---|---|
| General Objective | The main aim of the study; broader in scope | To evaluate the effectiveness of a nurse-led educational intervention on medication adherence among elderly patients with type 2 diabetes. |
| Specific Objectives | Detailed goals that break down the general objective |
1. To measure changes in medication adherence scores before and after the intervention. 2. To identify factors influencing adherence in the intervention group. 3. To compare adherence rates between intervention and control groups at 3-month follow-up. |
| Process Objectives | Focus on implementation aspects | To deliver six educational sessions to diabetic patients over a 12-week period. |
| Outcome Objectives | Focus on end results | To achieve a 20% improvement in HbA1c levels among participants by study completion. |
2.3 Characteristics of Good Research Objectives
- Specific: Clearly define what you’re investigating
- Measurable: Include variables that can be quantified or objectively assessed
- Achievable: Realistic within your time, resources, and ethical constraints
- Relevant: Connected to nursing practice and addressing meaningful gaps
- Time-bound: Specify the timeframe for achievement
Common Pitfalls:
- Objectives that are too broad or vague
- Including too many objectives in a single study
- Confusing objectives with methods or activities
- Formulating objectives that cannot be measured
- Setting unrealistic objectives given available resources
2.4 Step-by-Step Guide to Writing Objectives
- Begin with an action verb in the infinitive form (to determine, to identify, to compare, to assess, to evaluate, etc.)
- Specify what you want to learn about your research subject
- Identify the variables you’ll be examining
- Define the population you’re studying
- Note the context or setting when relevant
- Include a timeframe when appropriate
Example: Progressive Development of a Research Objective
Initial idea: Look at pain management in hospitals
Refined general objective: To evaluate pain management strategies in post-surgical patients
Final SMART objective: To determine the effectiveness of nurse-administered guided imagery compared to standard pain medication on reported pain scores (using the Numeric Pain Rating Scale) among adult patients during the first 72 hours following total knee replacement surgery at Memorial Hospital between January-June 2023.
3. Research Hypotheses: Testable Predictions
3.1 Definition and Purpose
A hypothesis is a formal, testable statement predicting the expected relationship between variables. While not all research requires hypotheses (particularly exploratory or qualitative studies), they are essential in quantitative research where statistical testing is involved.
Key Concept: A hypothesis bridges theory and observation. It translates your research question into a prediction that can be empirically tested.
3.2 Types of Hypotheses
| Type | Description | Example in Nursing Research |
|---|---|---|
| Research/Alternative Hypothesis (H₁ or Ha) | States the expected relationship between variables | Nurse-led diabetic education will significantly improve HbA1c levels compared to standard care. |
| Null Hypothesis (H₀) | States no relationship exists between variables | There is no difference in HbA1c levels between patients receiving nurse-led diabetic education and those receiving standard care. |
| Directional Hypothesis | Specifies the direction of the relationship | Nurse-led diabetic education will reduce HbA1c levels compared to standard care. |
| Non-directional Hypothesis | Predicts a relationship but not the direction | There will be a difference in HbA1c levels between patients receiving nurse-led diabetic education and those receiving standard care. |
| Simple Hypothesis | Predicts relationship between one independent and one dependent variable | Increased nurse staffing levels will reduce patient falls. |
| Complex Hypothesis | Predicts relationship between multiple variables | Increased nurse staffing levels will reduce patient falls, with the effect being stronger in geriatric units than in general medical units. |
3.3 Characteristics of Good Hypotheses
- Testable: Can be confirmed or refuted by empirical evidence
- Explicit: Clearly states the relationship between variables
- Specific: Precise in defining the variables and population
- Theoretically grounded: Based on existing knowledge or theory
- Ethical: Can be tested without violating ethical principles
- Defined: Uses operational definitions for key terms
Clinical Pearl: Strong hypotheses come from thorough literature reviews and clinical experience. When I mentor nurses new to research, I encourage them to immerse themselves in the literature before formulating hypotheses. This prevents “reinventing the wheel” or proposing hypotheses that previous research has already disproven.
3.4 Formulating Testable Hypotheses
- Identify variables: Clearly define independent and dependent variables
- Specify relationship: State how variables relate to each other
- Determine direction: Decide if you’re predicting the direction of effect
- Consider population: Define who the hypothesis applies to
- Make it testable: Ensure it can be evaluated with data
- Refine language: Use precise, unambiguous terminology
Critical Errors in Hypothesis Formulation:
- Creating hypotheses that cannot be falsified
- Using vague or ambiguous terminology
- Proposing relationships with no theoretical or empirical basis
- Confusing hypotheses with research questions or objectives
- Failing to operationally define key variables
- Creating hypotheses too complex to test in a single study
Example: Progressive Development of a Research Hypothesis
Research question: Does early mobilization affect recovery time after surgery?
Initial hypothesis: Early mobilization helps patients recover faster.
Improved hypothesis: Early mobilization reduces recovery time after surgery.
Final testable hypothesis: Patients who begin ambulation within 8 hours post-abdominal surgery will have a significantly shorter length of hospital stay (measured in days) compared to patients who begin ambulation after 24 hours post-surgery, controlling for age, surgical complexity, and comorbidities.
4. The Relationship Between Objectives and Hypotheses
Research objectives and hypotheses are complementary elements of research design, but they serve different functions:
| Research Objectives | Research Hypotheses |
|---|---|
| State what you want to accomplish | Predict outcomes or relationships |
| Always required in research | May not be needed in exploratory or qualitative research |
| Expressed as goals to achieve | Expressed as testable predictions |
| Begin with action verbs | State relationships between variables |
| Broader in scope | More specific and focused |
Key Concept: Not every research objective requires a corresponding hypothesis, particularly in descriptive or exploratory studies. However, every hypothesis should align with at least one research objective.
Example: Alignment Between Objectives and Hypotheses
Objective: To compare the effectiveness of two pain management protocols on post-operative pain levels in orthopedic patients.
Hypothesis: Patients receiving multimodal pain management protocol will report significantly lower pain scores (on the 0-10 Numeric Pain Rating Scale) during the first 48 hours post-surgery compared to patients receiving standard opioid-based pain management.
5. Practical Examples in Nursing Research
Case Study 1: Wound Care Research
Research Area: Pressure ulcer prevention
General Objective: To evaluate the effectiveness of a nurse-led pressure ulcer prevention protocol in intensive care units.
Specific Objectives:
- To determine the incidence of hospital-acquired pressure ulcers before and after implementation of the protocol.
- To identify factors associated with protocol adherence among ICU nursing staff.
- To assess the cost-effectiveness of the protocol compared to standard care.
Primary Hypothesis: Implementation of a nurse-led pressure ulcer prevention protocol in ICUs will significantly reduce the incidence of hospital-acquired pressure ulcers compared to standard care.
Secondary Hypothesis: ICU nurses with more years of experience will demonstrate higher adherence rates to the pressure ulcer prevention protocol than less experienced nurses.
Case Study 2: Mental Health Nursing Research
Research Area: Depression screening in primary care
General Objective: To evaluate the impact of nurse-administered depression screening on detection and treatment rates in primary care settings.
Specific Objectives:
- To compare depression detection rates between clinics using nurse-administered screening and those using standard practice.
- To measure time from screening to treatment initiation in identified cases.
- To assess patient satisfaction with the nurse-administered screening process.
Primary Hypothesis: Primary care clinics utilizing nurse-administered depression screening will identify significantly more cases of depression than clinics using physician-dependent identification methods.
Secondary Hypothesis: Patients identified through nurse-administered depression screening will begin treatment within a shorter timeframe than those identified through standard practice.
Clinical Pearl: In my experience supervising MSN and PhD student research, the most successful studies maintain clear alignment between objectives, hypotheses, and methodology. When these elements are congruent, the resulting research is not only more rigorous but also more likely to produce findings that can be translated into clinical practice.
6. Common Errors and How to Avoid Them
| Common Error | How to Avoid |
|---|---|
| Objectives that are too broad or vague | Use the SMART criteria to refine objectives; ensure each objective addresses only one aspect of research |
| Formulating untestable hypotheses | Ensure variables can be measured; specify the expected relationship clearly |
| Creating complex, unwieldy objectives | Break down complex objectives into multiple specific objectives |
| Misalignment between objectives and methodology | Verify that chosen methods can actually address each objective |
| Including too many objectives in one study | Focus on 3-5 key objectives that can be realistically accomplished |
| Confusing hypotheses with questions | Structure hypotheses as statements, not questions; include specific predicted relationships |
| Omitting null hypotheses in quantitative studies | Always formulate both alternative and null hypotheses for statistical testing |
| Setting objectives that don’t address research gaps | Conduct thorough literature review before finalizing objectives |
7. Practical Exercises for Developing Your Skills
Exercise 1: Refining Research Objectives
Take the following broad research interests and develop one general and three specific SMART objectives for each:
- Nursing handover communication
- Patient falls in long-term care
- Nurse burnout during pandemic conditions
Exercise 2: Hypothesis Formulation
For each of the following research objectives, formulate appropriate research hypotheses and corresponding null hypotheses:
- To compare the effectiveness of two different wound dressing protocols on healing time for diabetic foot ulcers.
- To determine the relationship between nurse staffing levels and medication administration errors on medical-surgical units.
- To evaluate the impact of a mindfulness-based stress reduction program on compassion fatigue among oncology nurses.
Exercise 3: Identifying Flaws
Identify the problems with these poorly written objectives and hypotheses, then rewrite them correctly:
- Objective: “To study pain in patients.”
- Hypothesis: “Nurse education is better.”
- Objective: “To determine incidence, prevalence, risk factors, complications, treatment options, and future directions for research regarding catheter-associated urinary tract infections in pediatric patients.”
8. Aligning Objectives and Hypotheses with Research Designs
| Research Design | Objective Characteristics | Hypothesis Considerations |
|---|---|---|
| Descriptive | Objectives focus on describing phenomena, populations, or situations (“to describe,” “to identify,” “to document”) | Formal hypotheses often unnecessary; research questions may be sufficient |
| Correlational | Objectives examine relationships between variables without manipulation (“to examine the relationship,” “to determine the association”) | Non-causal hypotheses predicting relationships between variables |
| Quasi-experimental | Objectives compare outcomes between groups with some control but without randomization (“to compare,” “to evaluate the effect”) | Hypotheses predicting differences between groups, acknowledging potential confounders |
| Experimental/RCT | Objectives focus on causal relationships with intervention and control groups (“to determine the effect,” “to test the efficacy”) | Precise causal hypotheses stating expected outcomes of interventions |
| Qualitative | Objectives aim to understand, explore, or describe experiences or phenomena (“to explore,” “to understand,” “to describe”) | Formal hypotheses typically not used; instead, research questions guide inquiry |
| Mixed Methods | Multiple objectives addressing both quantitative and qualitative aspects | Hypotheses for quantitative components; research questions for qualitative aspects |
Key Concept: Your research design should flow logically from your objectives and hypotheses, not the other way around. First determine what you want to accomplish (objectives) and what relationships you expect to find (hypotheses), then select the appropriate design.
9. From Objectives to Variables: Making the Connection
Each research objective should clearly identify the key variables in your study:
Example: Connecting Objectives to Variables
Objective: “To determine the effect of hourly nursing rounds (independent variable) on patient fall rates (dependent variable) in medical-surgical units.”
Variables identified:
- Independent variable: Hourly nursing rounds (yes/no or frequency)
- Dependent variable: Patient fall rates (falls per 1000 patient days)
- Potential confounding variables: Patient acuity, staffing levels, unit layout
Clinical Pearl: When teaching research methods to graduate nursing students, I’ve found that creating a variables map is extremely helpful. This involves listing all objectives, then identifying and classifying each variable (independent, dependent, confounding, mediating, etc.) and determining how each will be measured. This exercise reveals gaps or inconsistencies before data collection begins.
10. Summary: Essential Points to Remember
Research Objectives
- Serve as your research roadmap
- Should follow SMART criteria
- Begin with action verbs
- Include one general objective and several specific objectives
- Must align with your research question and design
- Should be achievable with available resources
Research Hypotheses
- Are testable predictions about relationships between variables
- Must be grounded in theory or prior evidence
- Should state relationships specifically and unambiguously
- Include both research (alternative) and null hypotheses in quantitative studies
- May not be necessary in exploratory or qualitative research
- Must use operationally defined variables
Final Note: Well-crafted objectives and hypotheses not only guide your research but also communicate your intentions clearly to others. When writing a research proposal or manuscript, these elements help reviewers, funders, and readers understand exactly what you set out to accomplish and why it matters to nursing practice.
11. References and Further Reading
- Creswell, J. W., & Creswell, J. D. (2018). Research design: Qualitative, quantitative, and mixed methods approaches (5th ed.). SAGE Publications.
- Gray, J. R., Grove, S. K., & Sutherland, S. (2021). Burns and Grove’s the practice of nursing research: Appraisal, synthesis, and generation of evidence (9th ed.). Elsevier.
- Hulley, S. B., Cummings, S. R., Browner, W. S., Grady, D. G., & Newman, T. B. (2013). Designing clinical research (4th ed.). Lippincott Williams & Wilkins.
- LoBiondo-Wood, G., & Haber, J. (2021). Nursing research: Methods and critical appraisal for evidence-based practice (10th ed.). Elsevier.
- Polit, D. F., & Beck, C. T. (2021). Nursing research: Generating and assessing evidence for nursing practice (11th ed.). Wolters Kluwer.