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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...

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: 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...

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...

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,...

Hazard Ratio

Hazard Ratio

The hazard ratio (HR) is a widely used measure in clinical trials to compare the risk of events, such as death or disease recurrence, between two groups over time. It reflects the ratio of hazard rates—the instantaneous risk of the event occurring—between a treatment group and a control group. This measure provides valuable insights into the relative effectiveness of a treatment by assessing how the risk of an event differs between the two groups.
For example, in a clinical trial...

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Related Experiment Video

Updated: Apr 16, 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

Retracted Randomized Clinical Trials From Superretractors and Top-Cited Scientists With Multiple Retractions.

Chunwei Lyu¹, Minoo Matbouriahi¹, Florian Naudet^2,3

¹Department of General Psychology, University of Padova, Padova, Italy.

JAMA Network Open

|April 15, 2026

Summary

A small group of highly cited authors, termed superretractors, significantly contributed to retracted randomized clinical trials (RCTs). These influential authors, often coauthors, were associated with earlier publications and retractions, and more citations.

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Area of Science:

Medical Ethics
Scientific Integrity
Bibliometrics

Background:

Multiple retractions by an author can indicate systemic issues like data fabrication or alteration.
Understanding the impact of prolific authors on retracted scientific literature is crucial for maintaining research integrity.

Purpose of the Study:

To assess the contribution of "superretractors" and highly cited scientists with multiple retractions to the body of retracted randomized clinical trials (RCTs).

Main Methods:

A retrospective cohort study analyzed retracted RCTs using the VITALITY database.
Authors were categorized into "superretractors" and top-cited scientists with 10+ retractions (career-long and recent).
Data on publication year, retraction year, time to retraction, and citations were compared.

Main Results:

A small number of "superretractors" (30) and top-cited scientists (163 career-long, 174 recent) were linked to 1330 retracted RCTs.
"Superretractors" coauthored 22% of retracted RCTs, with many also coauthored by top-cited scientists.
Articles involving "superretractors" were published and retracted earlier, had longer publication-to-retraction times, and received more citations.

Conclusions:

A disproportionate share of retracted RCTs are linked to a small group of influential "superretractors" and top-cited scientists.
These authors are often coauthors and concentrated in specific medical fields.
The findings highlight the need for greater scrutiny of influential authors contributing to retracted research.