Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Randomized Experiments

Randomized Experiments

The randomization process involves assigning study participants randomly to experimental or control groups based on their probability of being equally assigned. Randomization is meant to eliminate selection bias and balance known and unknown confounding factors so that the control group is similar to the treatment group as much as possible. A computer program and a random number generator can be used to assign participants to groups in a way that minimizes bias.
Simple randomization
Simple...

Blinding

Blinding

Blinding is a commonly used method of not telling participants which treatment a subject is receiving. Blinding is a critical part of a randomized control trial or RCT. It reduces the bias that affects the results. In an RCT, blinding is used in the form of a placebo. A placebo effect occurs when untreated subjects falsely believe they have received the treatment and report improved symptoms. A placebo or a dummy treatment is administered to subjects to negate the bias caused by such an effect.

Clinical Trials

Clinical Trials

Clinical trials are prospective experimental studies conducted on humans to determine the safety and efficacy of treatments, drugs, diet methods, and medical devices. Using statistics in clinical trials enables researchers to derive reasonable and accurate conclusions from the collected data, allowing them to make wise decisions in uncertain situations. In medical research, statistical methods are crucial for preventing errors and bias.
There are four phases in a clinical trial. A phase one...

Clinical Trials: Overview

Clinical Trials: Overview

Clinical development focuses on how the drug will interact with the human body and encompasses four key phases of clinical trials, each serving a specific purpose in assessing the safety and effectiveness of new drugs. These phases overlap and build upon one another. Phase I involves a small group of healthy volunteers (typically 20-80 individuals) or, in cases where significant toxicity is expected, patients with the targeted disease, such as cancer or AIDS. The volunteers are tested for...

Cluster Sampling Method

Cluster Sampling Method

Appropriate sampling methods ensure that samples are drawn without bias and accurately represent the population. Because measuring the entire population in a study is not practical, researchers use samples to represent the population of interest.
To choose a cluster sample, divide the population into clusters (groups) and then randomly select some of the clusters. All the members from these clusters are in the cluster sample. For example, if you randomly sample four departments from your...

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

Biopharmaceutical studies constitute a vital field aiming to enhance drug delivery methods and refine therapeutic approaches, drawing upon diverse interdisciplinary knowledge. In research methodologies, the choice between controlled and non-controlled studies significantly influences the study's reliability and accuracy.
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast, controlled...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Acceptability of, and preference for, human papillomavirus self-sampling for physically Disabled women: A cross-sectional survey.

Journal of medical screening·2026

Same author

Proxy consent to clinical research participation: how should it be justified?

Medicine, health care, and philosophy·2026

Same author

A Confucian Perspective on Public Health Ethics.

Bioethics·2026

Same author

Natural Language Processing to Build a Multicenter Computable Phenotype Library for Adults with Congenital Heart Disease.

medRxiv : the preprint server for health sciences·2025

Same author

Health among Retired Great Britain's Olympic Athletes: A cross-sectional Study of Disease and Multimorbidity.

Sports medicine - open·2025

Same author

BioImpedance Spectroscopy to maintain Renal Output: the BISTRO randomised controlled trial.

Health technology assessment (Winchester, England)·2025

Same journal

Erratum In: "Ogunbajo et al. Respond".

American journal of public health·2026

Same journal

The Role of Gender in HIV Care Engagement Among Individuals Assigned Male Sex at Birth: Medical Monitoring Project, United States, 2015-2022.

American journal of public health·2026

Same journal

Domestic Returns to Predictable US Participation in the World Health Organization: Health Security and Cost.

American journal of public health·2026

Same journal

The Risks of Mortality, Cardiovascular Events, and Pulmonary Complications in Cancer Patients Who Smoke Cigarettes and Switch to E-Cigarettes: South Korea, 2015‒2022.

American journal of public health·2026

Same journal

Retailers CARE Program in Montgomery County, Ohio, Partners With Alcohol, Tobacco, and Lottery Retailers to Promote Healthier Communities.

American journal of public health·2026

Same journal

Trends in Sexual Activity, Condom Use, and Use of Pregnancy Prevention Methods Among Female Adolescents: United States, 2007-2023.

American journal of public health·2026

See all related articles

Search research articles

Related Experiment Video

Updated: May 24, 2026

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

Published on: September 20, 2019

Informed consent and cluster-randomized trials.

Julius Sim¹, Angus Dawson

¹Arthritis Research UK Primary Care Centre, Keele University, Staffordshire, UK. j.sim@keele.ac.uk

American Journal of Public Health

|March 7, 2012

Summary

This summary is machine-generated.

Cluster-randomized trials are vital for public health interventions. Waiving individual informed consent may be ethically permissible for these studies if institutional review boards provide sufficient justification.

More Related Videos

Working with Human Tissues for Translational Cancer Research

Working with Human Tissues for Translational Cancer Research

Published on: November 26, 2015

E-Patient Counseling Trial (E-PACO): Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

E-Patient Counseling Trial (E-PACO): Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

Published on: August 1, 2019

Related Experiment Videos

Last Updated: May 24, 2026

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition

Published on: September 20, 2019

Working with Human Tissues for Translational Cancer Research

Working with Human Tissues for Translational Cancer Research

Published on: November 26, 2015

E-Patient Counseling Trial (E-PACO): Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

E-Patient Counseling Trial (E-PACO): Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

Published on: August 1, 2019

Area of Science:

Public Health
Clinical Trials Methodology
Bioethics

Background:

Cluster-randomized trials (CRTs) are crucial for evaluating public health interventions.
Obtaining individual informed consent in some CRTs can be impractical or conflict with study objectives.

Purpose of the Study:

To address the ethical considerations of omitting individual informed consent in CRTs.
To propose a framework for ethical approval of CRTs without individual consent.

Main Methods:

The study presents an argument based on ethical principles and methodological considerations.
It discusses the role of institutional review boards (IRBs) in evaluating consent waivers.

Main Results:

Individual informed consent may not always be feasible or appropriate in CRTs.
Ethical approval should not be automatically hindered by the absence of individual consent.

Conclusions:

Sufficient justification for omitting individual informed consent in CRTs is paramount.
Institutional review boards are best positioned to assess the ethical justification for proceeding without individual consent, prioritizing this over community or proxy consent.