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Related Concept Videos

Randomized Experiments01:13

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 Approaches01:23

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...
Random and Systematic Errors01:20

Random and Systematic Errors

Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be random or systematic. Random errors are observed due to the inconsistency or fluctuation in the measurement process, or variations in the quantity itself that is being measured. Such errors fluctuate from being greater than or less than the true value in repeated measurements. Consider a scientist measuring the length of an earthworm using a...
Random and Systematic Errors01:20

Random and Systematic Errors

Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be random or systematic. Random errors are observed due to the inconsistency or fluctuation in the measurement process, or variations in the quantity itself that is being measured. Such errors fluctuate from being greater than or less than the true value in repeated measurements. Consider a scientist measuring the length of an earthworm using a...
Dosage Regimen: Individualization01:24

Dosage Regimen: Individualization

Individualization in dosing regimens is the customization of medication doses for individual patients. Its necessity arises from the goal of maximizing therapeutic benefits while minimizing risks. This approach is pivotal because human responses to drugs can vary widely; what is effective for one person may be inadequate or excessive for another. Interpatient (intersubject) variability refers to differences in drug responses between individuals, while intrapatient (intrasubject) variability...
Regression Toward the Mean01:52

Regression Toward the Mean

Regression toward the mean (“RTM”) is a phenomenon in which extremely high or low values—for example, and individual’s blood pressure at a particular moment—appear closer to a group’s average upon remeasuring. Although this statistical peculiarity is the result of random error and chance, it has been problematic across various medical, scientific, financial and psychological applications. In particular, RTM, if not taken into account, can interfere when researchers try to extrapolate results...

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Related Experiment Video

Updated: Jun 20, 2026

The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials
08:36

The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials

Published on: April 19, 2024

Variation in results from randomized, controlled trials: stochastic or systematic?

Daniel Jane-wit1, Ralph I Horwitz, John Concato

  • 1Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA.

Journal of Clinical Epidemiology
|September 11, 2009
PubMed
Summary

Variations in treatment protocols, specifically drug dosages, in randomized controlled trials (RCTs) can lead to conflicting results. These discrepancies reflect a spectrum of real outcomes influenced by patient characteristics and intervention specifics.

Related Experiment Videos

Last Updated: Jun 20, 2026

The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials
08:36

The Adjuvant Efficacy of Angong Niuhuang Pill in the Treatment of Viral Encephalitis: A Meta-Analysis of Randomized Controlled Trials

Published on: April 19, 2024

Area of Science:

  • Clinical Research Methodology
  • Evidence-Based Medicine
  • Pharmacology

Background:

  • Randomized controlled trials (RCTs) are the gold standard for research evidence.
  • Conflicting results from RCTs investigating the same association are common.
  • Variability in study protocols may explain these discordant outcomes.

Purpose of the Study:

  • To investigate whether differing treatment protocols in RCTs contribute to disparate outcome patterns.
  • To assess the impact of variable pharmacologic dosing on trial results.

Main Methods:

  • A review of meta-analyses identified clinical topics with RCTs featuring variable dosing and outcomes.
  • Topics were selected if at least two pairs of trials showed contradictory strong exposure-outcome associations.
  • RCTs were categorized into low- and high-dose intervention groups.

Main Results:

  • Fifty-eight RCTs across six clinical topics were analyzed.
  • Aggregate odds ratios between low- and high-dose groups were frequently discordant.
  • Exploratory analysis showed statistically significant outcome differences in comparison arms between low- and high-dose groups for four of five topics.

Conclusions:

  • Conflicting RCT results can represent a spectrum of actual treatment outcomes.
  • Evaluating RCTs requires consideration of both study design validity and patient/intervention generalizability.
  • Dosage variations are a key factor in understanding outcome discrepancies in clinical trials.