Research Discussion 3

Please read the lecture and respond to the discussion questions in APA format with reference

Theory, Design, and Sampling


Understanding the component of the research process enables nurses to critically appraise the results to determine if practice needs to change, or how the findings enhance the body of knowledge associated with nursing science. This includes the theory underpinning the study, the variables being measured, the design to answer the question, and the population being studied.


Theoretical/Conceptual Framework

A theoretical framework allows researchers to link a large body of nursing knowledge to their study. The framework should be designed to describe the major components of the theory. The relational statements of the theory are tested, and not the theory as a whole. The framework may be expressed as a map or a diagram of the relationships. Every study has a framework, and a study that is based on a theory is said to have a theoretical framework.

Nurses may use a conceptual framework rather than a theoretical framework because existing theories in nursing are not sufficient or available. The goal of a conceptual framework is to explain the concepts used in the study and to identify the relationship between the concepts. The development of a conceptual process may be done in a two-step process (Burns & Grove, 2011):

Identify and examine the meanings of the concepts to be examined in the study.

Examine the relationship between the concepts and illustrate it in a model. This step is very important because it is the relationship which is tested in a study, and not merely the concepts.


A variable is that which is measured, controlled, or manipulated in a study. Variables can be identified as either independent or dependent. Independent variables can be manipulated in some way and are the presumed cause of outcome. Dependent variables may be used by a researcher to see if they will have a presumed effect on the outcome.

Extraneous Variables

In an ideal research study, all variables would be controlled except the one being manipulated. In reality, though, very few variables can be controlled. Extraneous variables are not controlled by the researcher but may nevertheless have an influence on the dependent variable. Extraneous variables may interfere with obtaining a clear understanding of the study dynamics. Therefore, researchers attempt to identify and control as many extraneous variables as possible. Quasi-experimental and experimental designs are developed to control extraneous variable influence. As the level of control decreases in the quantitative study, the influence of extraneous variables increases. An example of an extraneous variable is an environmental variable, such as climate (Brink & Wood, 1998).

Research Study Design

The research study design provides guidelines for the investigation and directs the selection of the population, as well as the data collection and analysis. The design organizes all of the components of the study and clearly defines the framework for the study. The design plans for limiting extraneous variables and maximizing control.


The purpose of the research study design is to achieve greater control over the validity of the study. Validity, one way to evaluate the research design, measures the accuracy of the claim. Types of validity include internal, construct, and external. Internal validity is the extent to which detected effects in the study are due to reality rather than to extraneous variables. The internal validity is especially important in the causal study, when the researcher examines whether the independent and dependent variables may have been affected by a third variable.


The population of the study consists of all elements that meet the inclusion criteria for the study. This criterion should be carefully defined to fit the most representative population. The population sample is the subset of the selected population. As the number of variables in a research study increases, the sample size increases.

Sampling Error

In the research study, the numerical value of the sample is a statistic. The numerical value of the population is a parameter. The difference between the two is called the sampling error. The sampling error usually decreases with increasing sample size. The sampling plan is developed to ensure precision in estimating the population parameters. The first step in sampling is to identify the population to be studied, the target population. There are several choices of sampling types including random/probability, nonprobability, convenience, and purposive (Cooper & Schindler, 2003).

Random/probability sampling provides a sample most representative of a population because each member has an equal chance of being chosen. Randomly selecting the target population is the ideal, but realistically, time and cost must be factored in. Therefore, a population must be identified that is accessible and representative in relation to the variables being examined.

Nonprobability sampling means that not every member of the population has the opportunity to be selected for the study sample.

Convenience sampling means that subjects are included because they were in the right place at the right time.

Purposive sampling is used when there is a conscious effort to select certain subjects.


There are three common research settings: natural, partially controlled, and highly controlled. Natural settings are real-life settings, and the environment is not manipulated or changed in any way. In the partially controlled setting, such as the hospital, the researcher manipulates the environment in some way. In the highly controlled setting, such as the laboratory, the researcher artificially constructs the environment for the purpose of the research study (Burns & Grove, 2011).


The research design, population, and setting are important components that help answer the research question and inform nurses if the findings will be relevant to their practice. For nurses to be consumers of research, being able to critique the theory that is being tested, determine if the design is appropriate to answer the question, and decide if the sample supports generalization, adds to knowledge translation. To help determine when research can be applied to their practice, they need to be able to critique these components for applicability to their practice and setting.


Brink, P. J., & Wood, M. J. (1998). Advanced design in nursing research (2nd ed.).

Thousand Oaks, CA: Sage.

Burns, N., & Grove, S. (2011). Understanding Nursing Research (5th ed.). Maryland Heights, MO: Elsevier. ISBN-13: 9781437707502

Cooper, D. R., & Schindler, P. S. (2003). Business research methods (8th ed.). Boston: McGraw-Hill Irwin.

Discussion 1

Provide examples of experimental and nonexperimental research design. Contrast the levels of control applied to each.

Discussion 2

What is sampling theory? Describe it and provide examples to illustrate your definition. Discuss generalizability as it applies to nursing research.

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