From the Guidelines
The answer is A. Statistics, as the reason for the choice of sample size should be contained in this section of the research protocol. The Statistics section typically includes the statistical methods that will be used to analyze the data, power calculations, and justification for the selected sample size, as recommended by the American Heart Association in their 2021 report 1. Sample size determination is a critical statistical consideration that directly impacts the study's ability to detect meaningful effects. Researchers need to explain how they calculated their sample size based on factors such as expected effect size, desired statistical power, significance level, and anticipated dropout rates. Including this information in the Statistics section ensures that reviewers and other researchers can evaluate whether the study is adequately powered to address its research questions and objectives. This placement is logical because sample size determination is fundamentally a statistical decision that affects the validity and reliability of the study's conclusions.
Some key points to consider when justifying sample size include:
- Providing justification of the final sample, whether driven by statistical considerations, logistical considerations, or other, as outlined in the 2021 American Heart Association report 1
- Specifying the outcome on which the calculation was based, the statistical test to be used, and any additional assumptions made, such as magnitude of between-group differences, variability of data, and duration of follow-up
- Including details relevant to the approach used, such as quantity of precision rather than being powered to detect a specific effect size, as recommended in the 2021 report 1.
While other sections, such as Study Objectives and Purposes, may provide context for the research question, the Statistics section is the most appropriate place to include the reason for the choice of sample size, as it is a critical statistical consideration that directly impacts the study's ability to detect meaningful effects, and is supported by the most recent and highest quality evidence 1.
From the Research
Research Protocol Structure
The research protocol should contain the reason for the choice of sample size in the section that outlines the methodology, specifically in the part that covers sample size calculation and sampling 2.
Methodology Section
This section should include:
- Study design and settings
- Study subjects
- Sample size calculation and sampling
- Participants recruitment and follow-up
- Questionnaire development
- Potential variables and outcomes
- Data analysis plan
Sample Size Calculation
The calculation of sample size requires information that must be supported by the research protocol, including:
- Objectives (descriptive study or a study to establish differences between groups)
- Hypotheses (with magnitude and direction)
- Scale of measurement of the outcome variable(s)
- Type I error and type II error appropriately identified 3
Protocol Writing
Writing a research protocol is a challenging task, and the quality of the protocol is crucial for academic and administrative success 4. The protocol should follow a standard format, including an abstract, study description, ethical considerations, significance of the study, budget, and description of the investigators 5.
Correct Answer
Based on the provided evidence, the correct answer is:
- A. Statistics (as part of the methodology section that covers sample size calculation and sampling) However, it's also closely related to:
- C. Data Management (as sample size calculation is crucial for data analysis) But most directly, the reason for the choice of sample size should be contained in the methodology section, which is not explicitly listed as an option. The closest match among the given options would be A. Statistics, as it is the section most closely related to sample size calculation.
Note: The provided options do not exactly match the structure outlined in the evidence, but based on the information given, A. Statistics is the most appropriate choice.