A research design and a sampling strategy are among the most important factors determining the accuracy of the results obtained in the course of the nursing study. The former refers to the framework selected by the researcher to organize the constituents of the study (data collection, measurement, and analysis) in such a way that it could successfully address a particular problem. A sample can be defined as a subset of a population group selected for testing the hypothesis of the study.
The proposed study hypothesizes that radical alterations in patients behavior, dietary habits, and physical activity are the most efficient ways to manage obesity and improve the quality of life. To test this hypothesis, it is necessary to compare the effect of the suggested interventions with the ones of bariatric surgery.
The following criteria will be used for inclusion/exclusion:
- being/not being over 18 (since the study is aimed to investigate the problem in adult patients) and under 65 (as no side conditions should interfere with the clinical picture);
- having/not having the BMI over 30;
- having bariatric surgery (for one group);
- having no surgical interventions (for the other group).
The sample will include 120 patients in total; data are to be collected in general care units. Since the majority of patients do not need hospitalization (excluding cases of severe obesity), they can introduce the suggested intervention in their home settings and come only for screenings.
The major sampling strategy is to divide the participants into two groups, each including 60 patients: the control group (those who have undergone bariatric surgery) and the intervention group (those whose obesity will be treated with the help of diet and physical exercise). While the first group will be monitored to check how stable their surgery results are, the second group will be provided with exercise and nutrition strategies to manage the problem. The sampling procedure will require taking several steps:
- identifying criteria for eligibility;
- selecting a sample of patients aged 18-65 with a BMI over 30 (including those who have and have not undergone bariatric surgery);
- informing the participants about the purpose of the study and obtaining their written consent:
- collecting background information about those enrolled;
- dividing the participants into two groups (control and intervention) (Parahoo, 2014).
The approach used for the study is quantitative since it will have to deal with numerical indicators. As the hypothesis is to be tested through a particular intervention, it is reasonable to opt for the experimental design. This will make it possible not only to collect valuable evidence but also to help real patients improve their quality of life. Moreover, strict experiment regulations and measures will ensure better control of the conditions (Grove, Burns, & Gray, 2014).
Choosing an unsuitable research design or conducting an experiment with the wrong sample can give inaccurate or misleading results. Such outcomes deprive the study of its external validity. This implies that they cannot be generalized for the selected population and will be attributed exclusively to the sample under the analysis.
To avoid this, all the steps of the sampling strategy were carefully elaborated for the proposed study. The criteria for inclusion/exclusion of the participants were also specified. Finally, the rationale for the selected design was provided.
In the course of the experiment, the research is trying to find out how independent variables influence dependent ones. All other variables not directly related to the study must be neutralized. Otherwise, the accuracy of the results will be negatively affected. Other aspects to be considered as per the statistical significance of the study are the validity and reliability of the selected instrument. These two principles are critical attributes of the scientific method in nursing research.
Reliability of the study refers to its inherent repeatability, which implies that it can be performed by other researchers and will generate the same outcomes (provided that the conditions and instruments are also the same). Validity is aimed to show whether the study aligns with the scientific method and if its instruments perform their designated functions. The paper at hand will apply the above-mentioned concepts to the proposed study.
Extraneous variables are those that are not needed for the study since they can affect the results in an undesirable manner. Such variables are difficult to predict. Unless their effect is mitigated or eliminated, they can add errors to the experiment. In the suggested study, the following extraneous variables are to be controlled:
- Experimenter effects: The clinical picture might be distorted by the researcher’s subjective attitude to the participants’ achievements in weight loss. To avoid this, the author of the experiment must exclude any other criteria except the BMI.
- Demand characteristics: The participants may start starving themselves or overexercising if they know what outcome the researcher wants to achieve. This can be avoided by giving them no preliminary information about the desired results.
- Participant variables: Obesity can be aggravated by other diseases (e.g., heart conditions, hormonal deregulations, etc.). Thus, patients having such conditions should not be included in the sample.
- Situational variables: The condition of the patient may be affected by his/her socioeconomic status. Random sampling is necessary to eliminate these side effects (Houser, 2016).
Instruments: Validity and Reliability Estimates
120 patients are to be selected for the experiment to compare the effects of bariatric surgery with those of physical activity and healthy nutrition on obese patients’ THE BMI. To choose the most suitable instrument to assess the results, it is necessary to estimate which one has the highest validity and reliability. Since objective indicators are more reliable than patient-reported data, objective measurements of the BMI were selected.
This allows repetition of the obtained results, using the same method. Validity (the extent to which the tool performs its designed function) is supported by the studies on the accuracy of the BMI in identifying obesity: The number of false positives (people classified as obese without actually having this problem) is very small (less than 1% in women and 5% in men). Validity and reliability of generating the researcher’s instruments will be tested by
- objectiveness of the criteria;
- generalizability of the results;
- consistency of measure;
- comparability with the data collected by other researchers;
- responsiveness of the tool (its ability to reflect changes happening to the participants).
Description of the Intervention
The research is going to identify whether proper nutrition and physical activity are more effective in decreasing obesity in patients aged 18-65 than bariatric surgery. The patients will be selected from the same hospital to ensure that environment does not interfere with the results as an extraneous variable. The research will be a quantitative experimental study investigating the causal relationships between obesity and two intervention strategies.
The patients will be divided into two groups: While the former will include those who have already undergone bariatric surgery, the latter will consist of patients whose obesity will be managed through physical activity and dieting. At the end of the experiment (which is going to last for approximately five months), the BMI will be measured for both groups.
Data Collection Procedures
The data collection procedure will take the following steps:
- choosing 120 patients aged 18-65 and suffering from obesity;
- explaining the goal of the study and obtaining the participants’ written consent;
- dividing the patients into two groups (control and intervention);
- measuring the BMI and collecting patient-reported information concerning health habits;
- organizing a 5-month plan of physical activity and dieting for the intervention group;
- measuring the BMI in both groups and comparing the results.
It was found out that all the extraneous variables that may appear in the course of the study (experimenter effects, demand characteristics, participant variables, and situational variables) can be neutralized, which will considerably increase the accuracy of the results. The BMI chosen as the major instrument for measuring the outcomes was proven to have high validity and reliability. The suggested data collection procedure will also contribute to the quality of the obtained results.
It is not enough to collect data from the sample population. It would be impossible to conclude the experiment unless statistical information is properly analyzed. For this purpose, tools of descriptive and inferential statistics are applied. The paper at hand will provide a rationale for selecting particular instruments for the analysis of both demographic and study variables.
Data Analysis Plans for Demographic Variables
For analyzing demographic variables, the mean (or the arithmetic average) will be used as the most suitable measure of central tendency. It is calculated by dividing the sum of all scored by their total number. Although there is a limitation that the results can be affected by extreme variables, it will be eliminated by excluding participants under 18 and over 65.
Data Analysis Plans for Study Variables
Mean will also be used to measure the average BMI to ensure that it is more or less equal for both groups at the beginning of the experiment. T-test was selected to assess the outcomes of the intervention for the following reasons: 1) it is suitable for the small size of the sample (less than 200 participants); 2) it is easy to calculate; 3) it involves repeated measures; 3) it allows comparing groups measured on the same variables. This strategy seems reasonable since it makes it possible to estimate the effect of each of the two interventions (bariatric surgery and physical activity plus dieting). Other reasons to implement this instrument include:
- the simplicity of interpretation (it is much easier to see the difference between the groups because the t-test shows how different the mean of the control group is from that of the intervention group);
- robustness (the test allows samples from the two population samples with non-similar incoming demographic variables);
- ease of data collection (the test requires very little integral data; it can be performed based on only one value obtained from each subject) (Suresh, 2014).
As soon as the test is performed, the researcher will compare, which intervention was more effective based on the BMI changes in both groups.
Statistics are particularly useful for researchers of many fields as it allows them to arrange, analyze, and synthesize data. Furthermore, statistical tools may assist in communicating findings since they ensure the credibility of the study procedures, and conclusions are drawn. The T-test will be used for the proposed research since will ensure the ease of calculation and data collection as well as the robustness of the results and the simplicity of the interpretation.
Grove, S. K., Burns, N., & Gray, J. (2014). Understanding nursing research: Building an evidence-based practice (6th ed.). Amsterdam, Netherlands: Elsevier Health Sciences.
Houser, J. (2016). Nursing research: Reading, using and creating evidence (4th ed.). Burlington, MA: Jones & Bartlett Learning.
Parahoo, K. (2014). Nursing research: Principles, process and issues (3rd ed.) Basingstoke, UK: Palgrave Macmillan.
Suresh, S. (2014). Nursing research and statistics (2nd ed.). Amsterdam, Netherlands: Elsevier Health Sciences.