Sampling and Ethics in EBP Nursing Literature Research Papers
Sampling
This week, we continue our exploration of the steps of the research process. Previously, we examined the background, literature review, research problem, research purpose, research question, and research design. All of these elements are part of the planning phase. Next, we begin to look at the implementation of the plan, which is typically found in the methods section of the research report.
The setting for the study is the place where data collection occurs; this may be in a hospital, clinic, school, home, or other locations. The setting may indicate if the research was conducted in a rural or urban setting, a large or small setting, and so forth. Look to see how well the characteristics of the setting match your own setting—the closer the resemblance, the more applicable the evidence yielded from the research may be.
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When a population is identified for investigation, it is seldom realistic, or even essential, to conduct research on the entire population in order to collect reliable and valid data. Instead, a sample of the population representative of the characteristics of that population is chosen for study.
The sampling strategy is important because a significant sampling error could distort the findings and render them unreliable, invalid, and/or not able to be generalized by the entire population. The sampling strategy considers how subjects are recruited, selected, and, when appropriate, assigned to groups. The sampling strategy must meet all legal and ethical requirements.
There are two major categories of sampling: (a) probability, also known as random sampling, and (b) nonprobability sampling.
Probability or Random Sampling
Probability in sampling increases the chances that the sample accurately represents the population. Probability sampling is preferred in quantitative research because the goal is to generalize findings from the sample to the population. Probability sampling is not appropriate for qualitative studies because this type of research does not seek to generalize results. Two criteria must be met for achieving a probability sample—random selection and independent selection. Sampling and Ethics in EBP Nursing Literature Research Papers.
Random selection
In probability sampling, ideally, every member of the population has the same chance to be selected as a subject, but sampling the entire population is rarely feasible and, therefore, seldom used.
Random sampling
involves choosing subjects at random from the population. This strategy should evenly distribute characteristics found in the population to the sample. These characteristics are called extraneous variables (EV). Extraneous variables are not the focus of the research study, but their presence may influence the dependent variable (DV), or outcome. Although random sampling is easier to achieve than sampling the entire population, random sampling may still be labor intensive. Sampling and Ethics in EBP Nursing Literature Research Papers.
Random assignment
is much more likely to be the sampling strategy chosen by the researcher. First, the researcher selects subjects who meet certain criteria found in the population. Next, the researcher randomly assigns the subjects to groups to increase the likelihood that any characteristics (EVs) that might affect the outcome (DV) will be equally distributed among the groups. Random assignment to groups is the major way to control for EVs in experimental studies. Sampling and Ethics in EBP Nursing Literature Research Papers.
Earlier, it was mentioned that random assignment starts with selecting subjects. The aim is to recruit and select subjects who meet criteria found in the population.
Inclusion criteria
are characteristics of potential subjects that make them eligible to be included in the sample.
Exclusion criteria
are characteristics of potential subjects that make them ineligible for the sample.
Example:
If you wish to conduct research on adults, inclusion criteria might state that the subjects must be 21 years of age or older. Conversely, exclusion criteria would eliminate anyone under the age of 21. Sampling and Ethics in EBP Nursing Literature Research Papers.
The concern with overuse of inclusion and exclusion criteria is that they make the sample more homogeneous and the results less able to be generalized to the entire population.
Independent selection
The second criterion for achieving a probability sample is independent selection. This means that the selection of one subject is independent, or separate, from the selection of another. If independence is violated, the subjects may share characteristics that will show a correlation due to the sampling strategy instead of the effect of the independent variable (IV). Data results could be distorted.
Nonprobability Sampling
Nonprobability sampling involves a strategy where subjects are not selected at random. Instead, they may be chosen as part of a convenience sample, or a purposive sample.
Convenience sample
The convenience sample is the most common strategy. As the name implies, the subjects are chosen by the researcher because they are accessible. The weakness of convenience sampling is that the characteristics (EVs) of the population are less likely to be distributed evenly among the sample. Bias may occur that will negatively influence the outcomes (DV) of the research. The researcher may decide to use a convenience sample to recruit and select subjects and then make random assignments to groups to minimize the chance of bias by evening distribution of EVs over all groups. Convenience sampling is used for both quantitative and qualitative studies. Sampling and Ethics in EBP Nursing Literature Research Papers.
Purposive sample
The purposive sample is one where selection of subjects is intentional, or done on purpose. This is a common strategy in qualitative studies where probability sampling is not needed because there is no need for generalization to a larger population. Subjects are carefully chosen for their ability to inform and enlighten the researcher about a phenomenon or other aspect of the research question under consideration.
Sample Size and Power
Sample size
is the number of subjects that are studied. Qualitative studies may have rules and criteria for what is an appropriate sample size, but they are not as strict as those for quantitative studies. A case study may have only one subject. Typically, the researcher will recruit and collect data on subjects until
saturation
is reached, which is the point at which the researcher determines no new results are emerging. Saturation is one way to build confidence in the results of a qualitative study.
In quantitative research, a
power analysis
determines how large a sample should be to yield statistically significant results. In general, the sample size for a quantitative study must be a minimum of 30 subjects per group. Generally, larger sample sizes increase the likelihood that the researcher will notice subtle differences among groups. In addition, larger samples have more power and are less likely to produce results that are due to errors in sampling.
The researcher may report the number of subjects who were recruited, the number that consented to participate, and the number that dropped out during the study. Bias may be detected if a certain segment of the population was not represented in the final results because they were not recruited, did not consent, or dropped out. When the potential for bias exists, the trustworthiness of the findings may come into question. Sampling and Ethics in EBP Nursing Literature Research Papers.
When you read the research report, look for a description of the sampling strategy and how it was applied. Does the strategy fit with the research design? If this was a quantitative study, were there enough subjects to generalize the findings to the population? If this was a qualitative study, was saturation reached? These factors and more should be considered when you are selecting research-based evidence to apply to your practice.
Ethical Aspects of Research
Researchers must adhere to ethical standards throughout all steps of the research process. They must decide what choices are right or wrong and make value judgments to ensure the ethical treatment of everyone.
Research on human subjects has a murky history. The German Nazis conducted experiments on detainees in concentration camps during World War II. The Nazis were found guilty of atrocities during the Nuremberg war crimes trials, leading to the development of the Nuremberg Code in 1949, which still serves as the foundation of international guidelines for researchers (Houser, 2018). The tenets of the code include the following.
Research can only be undertaken when there are no other means to obtain knowledge.
Participation must be voluntary. Subjects can withdraw at any time.
Subjects must be made aware of risks and give informed consent.
No research can be conducted that could lead to death or disability.
The Declaration of Helsinki, first adopted in 1964, expanded the code (Houser, 2018).
The U.S. Public Health Service (2009) conducted research on African-American sharecroppers with syphilis between 1932 and 1972 to find out how the disease would progress if left untreated. The scientists did not tell the subjects that they had syphilis and withheld penicillin after it became standard treatment in the 1940s. Numerous subjects and their wives died from complications due to syphilis, and children were born with congenital syphilis. Sampling and Ethics in EBP Nursing Literature Research Papers.
Question & Answer
Question
The outrage over the Tuskegee study prompted the U.S. Congress to pass the National Research Act in 1974 (Houser, 2018). The act created the National Commission for Protection of Human Subjects of Biomedical and Behavioral Research. The commission was charged with writing the Belmont Report. This 1979 report describes principles that form the foundation of ethical treatment of human subjects (Houser, 2018). What are these principles, and what does each mean for the researcher?
Answer
The first principle is respect for persons. Individuals should be allowed to make their own decisions, and those who can’t make decisions for themselves or are vulnerable, need to be protected from harm. The second principle is beneficence, which means that researchers will maximize any benefits and minimize any harm to the subjects. The third principle is justice, which means subjects will be treated fairly during selection in terms of the benefits and burdens of research. Those who are disadvantaged will not be excluded from research that would benefit them, nor will they be put at risk from research that would harm them.
Legal Aspects of Research
Various laws govern the conduct of research on human subjects.
Common law, which includes medical malpractice
Administrative law, which is enacted by the federal government, such as HIPAA
Statutory law, which is enacted by the legislature
Tort law, which covers negligence, assault, false imprisonment, and invasion of privacy
The U.S. Department of Health and Human Services developed the Code of Federal Regulations (CFR) (Houser, 2018). The CFR mandated that Institutional Review Boards (IRB) be formed by organizations performing research to protect the rights of human subjects against unethical, unlawful, and inhumane treatment. The federal regulations stipulate the composition of IRB boards and their powers and responsibilities. Researchers must submit their proposals to the IRB for approval before their studies can be carried out.
Research misconduct can occur when the researcher intentionally makes up data, omits data, or changes data to manipulate the results. Plagiarism, or claiming another’s work as one’s own, is another form of research misconduct. When misconduct occurs, it erodes the trust of the public in the findings of all research. Sampling and Ethics in EBP Nursing Literature Research Papers.
Discussions this week instruct you to read one article and post what you learned about ethical and legal issues. This article will help you gain insight into the ethical and legal dilemmas that researchers face when planning and implementing their studies.
Summary
This lesson began our exploration of the implementation of the research process that is usually found in the report in the methods section. We looked at various sampling strategies and the reasons why they may be selected.
Next, we reviewed the ethical standards that must be followed when conducting research on human subjects and how these have evolved. Finally, we examined laws and regulations that govern research and how they can be violated.
Take the Check Your Knowledge Quiz to see how well you understand the concepts offered in your text and this lesson.
References
Houser, J. (2018).
Nursing research: Reading, using, and creating evidence
(4th ed.). Sudbury, MA: Jones and Bartlett.
U. S. Public Health Service syphilis study at Tuskegee
. (2009). Center for Disease Control and Prevention. Retrieved from http://www.cdc.gov/tuskegee/timeline.htm. Sampling and Ethics in EBP Nursing Literature Research Papers