Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Study Designs in Epidemiology01:20

Study Designs in Epidemiology

288
Epidemiological study designs are fundamental tools for investigating the distribution, determinants, and control of health conditions in populations. They help researchers understand the relationships between exposures and outcomes, and they broadly fall into two categories: "observational" and "experimental" studies.
Observational studies are those where the researcher does not intervene but rather observes natural variations. They include cross-sectional, cohort, and...
288
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches01:23

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

148
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,...
148
Clinical Trials01:16

Clinical Trials

6.9K
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...
6.9K
What is an Experiment?01:12

What is an Experiment?

11.8K
An experiment is a planned activity carried out under controlled conditions. The purpose of an experiment is to investigate the relationship between two variables. When one variable causes change in another, we call the first variable the explanatory or independent variable. The affected variable is called the response or dependent variable. In a randomized experiment, the researcher manipulates values of the explanatory variable and measures the resulting changes in the response variable. The...
11.8K
Randomized Experiments01:13

Randomized Experiments

7.1K
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...
7.1K
Comparing the Survival Analysis of Two or More Groups01:20

Comparing the Survival Analysis of Two or More Groups

228
Survival analysis is a cornerstone of medical research, used to evaluate the time until an event of interest occurs, such as death, disease recurrence, or recovery. Unlike standard statistical methods, survival analysis is particularly adept at handling censored data—instances where the event has not occurred for some participants by the end of the study or remains unobserved. To address these unique challenges, specialized techniques like the Kaplan-Meier estimator, log-rank test, and...
228

You might also read

Related Articles

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

Sort by
Same author

Exposure to air and water pollution during pregnancy and risk of adverse perinatal outcomes in São Paulo State: protocol for a retrospective population-based cohort study.

BMJ public health·2026
Same author

Changes in resource insecurity, sexual and mental health among young women after Kenya's 2024 heavy rains and floods.

International health·2026
Same author

Examining pathways between stigma, extreme weather exposure, resource insecurities and ART adherence among young men who have sex with men and female sex workers living with HIV in Kampala, Uganda.

HIV medicine·2026
Same author

Effects of Short-Term Versus Long-Term Mentalization-Based Therapy on Psychiatric Symptoms in Outpatients With Borderline Personality Disorder: Exploratory Results From a Randomized Clinical Trial.

Personality and mental health·2026
Same author

Values, preferences, and informational needs of individuals living with ANCA-associated vasculitis: a systematic review.

Rheumatology advances in practice·2026
Same author

Effects of Sedation, TEmperature and Pressure After Cardiac Arrest and REsuscitation on Major Adverse Kidney Events (STEPCARE-MAKE): A Protocol for a Pre-Planned Sub-Study of a Randomized Clinical Trial.

Acta anaesthesiologica Scandinavica·2026
Same journal

Cohort profile: Sheyang Mini Birth Cohort Study (SMBCS).

BMJ open·2026
Same journal

Quebec lung, liver and heart transplant recipients' perspectives on self-narratives and their experiences in creative writing workshops during the transplantation journey: a qualitative study.

BMJ open·2026
Same journal

Impact of climatic variables on postoperative outcomes in various surgical disciplines: a systematic review.

BMJ open·2026
Same journal

ADHD and cardiometabolic risk profile in adults with type 2 diabetes: a longitudinal register-based study.

BMJ open·2026
Same journal

Understanding the impact of the follow-up period on the association between excess body weight, and cardiovascular events and mortality: a prospective cohort study of the UK Biobank.

BMJ open·2026
Same journal

Temporal associations between incident physical health problems/sensory impairments and challenging behaviours in people with intellectual disabilities: a population-based longitudinal cohort study of primary care in England.

BMJ open·2026
See all related articles

Related Experiment Video

Updated: Jul 26, 2025

Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index
06:55

Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index

Published on: January 8, 2020

14.5K

Observed intervention effects for mortality in randomised clinical trials: a methodological study protocol.

Mathias Lühr Hansen1,2, Caroline Kamp Jørgensen2,3, Lehana Thabane4,5

  • 1Department of Neonatology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark mathias.luehr.hansen@regionh.dk.

BMJ Open
|June 14, 2023
PubMed
Summary
This summary is machine-generated.

Researchers analyzed intervention effects on all-cause mortality in randomized clinical trials. Findings reveal a tendency for inflated intervention effect estimates, impacting sample size calculations in medical research.

Keywords:
ACCIDENT & EMERGENCY MEDICINEANAESTHETICSINTENSIVE & CRITICAL CARE

More Related Videos

Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies
10:38

Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies

Published on: January 16, 2019

20.3K
A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
00:04

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

Published on: September 20, 2019

10.7K

Related Experiment Videos

Last Updated: Jul 26, 2025

Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index
06:55

Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index

Published on: January 8, 2020

14.5K
Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies
10:38

Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies

Published on: January 16, 2019

20.3K
A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
00:04

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

Published on: September 20, 2019

10.7K

Area of Science:

  • Clinical Trials Methodology
  • Biostatistics
  • Evidence-Based Medicine

Background:

  • Accurate sample size calculation in randomized clinical trials (RCTs) relies on realistic anticipated intervention effects.
  • Observed intervention effects in RCTs are frequently inflated compared to true effects, a phenomenon noted in critical care mortality trials.
  • This inflation pattern may extend across various medical specialties, potentially compromising trial design and interpretation.

Purpose of the Study:

  • To estimate the range of observed intervention effects for all-cause mortality in RCTs.
  • To analyze these effects across different Cochrane Review Groups to identify specialty-specific patterns.
  • To provide data for more accurate sample size estimations in future clinical trials.

Main Methods:

  • Inclusion of RCTs assessing all-cause mortality from Cochrane Reviews.
  • Clustering of trials by Cochrane Review Group for stratified statistical analysis.
  • Reporting of median relative risk, interquartile range (IQR), and distribution of relative risks across predefined ranges (e.g., <0.70, 0.70-0.79, etc.).
  • Subgroup analyses to explore factors influencing intervention effects (e.g., study design, sample size, risk of bias, funding).

Main Results:

  • Analysis of intervention effect sizes for all-cause mortality across diverse medical specialties.
  • Quantification of the median relative risk and variability in intervention effects.
  • Identification of the proportion of trials falling into specific relative risk categories.

Conclusions:

  • The study provides crucial data on the magnitude of intervention effects in RCTs concerning all-cause mortality.
  • Findings will inform more realistic assumptions for sample size calculations, enhancing the efficiency and reliability of clinical trials.
  • Understanding intervention effect inflation is vital for improving the design and interpretation of medical research.