At what stages of a research study can biases occur: during designing a study, study implementation, data analysis, or any of the above stages?

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From the Guidelines

The correct answer is d) Any of the above stages, as biases can occur throughout the entire research process, from initial design to final analysis, and can be influenced by various factors, including selection bias, performance bias, measurement/detection bias, and attrition/exclusion bias, as noted in 1. Biases can emerge during study design, such as selection bias, when researchers choose non-representative samples or create flawed inclusion criteria.

  • In the implementation phase, measurement bias, interviewer bias, or participant response bias can distort data collection, as discussed in 1.
  • During data analysis, biases can manifest through inappropriate statistical methods, selective reporting of results, or confirmation bias, where researchers favor data supporting their hypotheses, as mentioned in 1. These biases threaten the validity and reliability of research findings, potentially leading to incorrect conclusions.
  • Researchers must implement specific strategies at each stage to minimize bias, such as randomization, blinding procedures, standardized protocols, and transparent reporting of all results, including negative findings, as suggested in 1. It is essential to consider the potential sources of bias and take steps to mitigate them to ensure the accuracy and reliability of research findings.
  • The most recent study, 1, highlights the importance of developing causal directed acyclic graphs for observational health research, which can help identify potential biases and improve the validity of research findings.

From the Research

Biases in Research Studies

Biases can occur during various stages of a research study, including:

  • Designing a study: This stage is prone to biases such as selection bias, where the sample selected may not be representative of the population 2, 3.
  • Study implementation: Biases can occur during the execution of the intervention, measurement of exposures and outcomes, and data collection 2, 3.
  • Data analysis: Biases can occur during data analysis, such as confirmation bias, where researchers may interpret results in a way that confirms their hypotheses 2, 3.

Stages of Research Prone to Biases

Any of the above stages can be prone to biases, as biases can occur at various points in the research process, from literature review and publication to interpretation and publication of results 2, 3. Some studies have shown that understanding research bias is essential for critically reviewing the scientific literature and avoiding suboptimal or potentially harmful treatments 3. However, not all studies directly address the question of at which stage biases can occur, such as studies focused on the efficacy of specific vaccines 4, 5, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Definitions of Bias in Clinical Research.

Methods in molecular biology (Clifton, N.J.), 2021

Research

Identifying and avoiding bias in research.

Plastic and reconstructive surgery, 2010

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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