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

Bias in Epidemiological Studies01:29

Bias in Epidemiological Studies

1.6K
Biases can arise at various stages of research, from study design and data collection to analysis and interpretation. Recognizing and addressing these biases is essential to ensure the validity and reliability of epidemiological findings.Broadly speaking, biases in epidemiology fall into three main categories: selection bias, information bias, and confounding. A more detailed description of possible biases is:  
1.6K
Friedman Two-way Analysis of Variance by Ranks01:21

Friedman Two-way Analysis of Variance by Ranks

594
Friedman's Two-Way Analysis of Variance by Ranks is a nonparametric test designed to identify differences across multiple test attempts when traditional assumptions of normality and equal variances do not apply. Unlike conventional ANOVA, which requires normally distributed data with equal variances, Friedman's test is ideal for ordinal or non-normally distributed data, making it particularly useful for analyzing dependent samples, such as matched subjects over time or repeated measures...
594
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches01:23

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

627
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,...
627
Reliability and Validity01:29

Reliability and Validity

12.9K
Reliability and validity are two important considerations that must be made with any type of data collection. Reliability refers to the ability to consistently produce a given result. In the context of psychological research, this would mean that any instruments or tools used to collect data do so in consistent, reproducible ways.
12.9K
Variability: Analysis01:11

Variability: Analysis

944
Measures of variability are statistical metrics that reveal the dispersion pattern within a dataset. They are pivotal in biostatistics, providing insights into the heterogeneity within health and biological data. Variability signifies the degree to which data points diverge from one another, helping researchers understand the potential range of values and associated uncertainty within the data.
The range is a simple measure of variability, indicating the difference between the highest and...
944
Blind Procedures02:07

Blind Procedures

10.8K
Ideally, the people who observe and record the children’s behavior are unaware of who was assigned to the experimental or control group, in order to control for experimenter bias. Experimenter bias refers to the possibility that a researcher’s expectations might skew the results of the study. Remember, conducting an experiment requires a lot of planning, and the people involved in the research project have a vested interest in supporting their hypotheses. If the observers knew which...
10.8K

You might also read

Related Articles

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

Sort by
Same author

Tracking COVID-19 Severity and Progression Through Amines and Lipid Mediators.

Journal of medical virology·2026
Same author

Venous thromboembolism after mechanical restraint in psychiatric hospitals: population based cohort and self-controlled case series study.

BMJ (Clinical research ed.)·2026
Same author

Between-centre variation in antibiotic therapeutic drug monitoring and obtaining surveillance cultures in Dutch ICUs: A retrospective observational study.

Journal of critical care·2026
Same author

[Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration - a Korean translation].

Ewha medical journal·2025
Same author

Re: Comparison of the Test-negative Design and Cohort Design With Explicit Target Trial Emulation for Evaluating COVID-19 Vaccine Effectiveness.

Epidemiology (Cambridge, Mass.)·2025
Same author

Development and validation of artificial intelligence models for early detection of postoperative infections (PERISCOPE): a multicentre study using electronic health record data.

The Lancet regional health. Europe·2024

Related Experiment Video

Updated: Apr 26, 2026

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

14.3K

Physician's preference-based instrumental variable analysis: is it valid and useful in a moderate-sized study?

Anna G C Boef1, Judith van Paassen, M Sesmu Arbous

  • 1From the aDepartment of Clinical Epidemiology; bDepartment of Intensive Care; cDepartment of Medical Statistics and Bioinformatics; and dDepartment of Endocrinology and Metabolic Diseases, Leiden University Medical Centre, Leiden, The Netherlands.

Epidemiology (Cambridge, Mass.)
|July 23, 2014
PubMed
Summary
This summary is machine-generated.

Instrumental variable analysis in cardiac surgery showed similar trends but wider confidence intervals than randomized trials. Statistical precision limitations reduce its usefulness in moderate-sized studies.

Related Experiment Videos

Last Updated: Apr 26, 2026

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

14.3K

Area of Science:

  • Biostatistics
  • Cardiovascular Surgery
  • Observational Data Analysis

Background:

  • Instrumental variable (IV) methods offer a potential solution to unmeasured confounding in observational studies.
  • Physician's preference IV analysis is explored for its validity and utility in clinical research.

Purpose of the Study:

  • To assess the validity and usefulness of physician's preference IV analysis in a moderate-sized clinical study.
  • To evaluate the effect of preoperative corticosteroids on patient outcomes following elective cardiac surgery.

Main Methods:

  • Utilized routine care data from 476 elective cardiac surgery patients.
  • Applied physician's preference instrumental variable analysis.
  • Assessed outcomes including mechanical ventilation time, ICU and hospital stay, infections, atrial fibrillation, heart failure, and delirium.

Main Results:

  • Physician's preference IV analysis results aligned directionally with a large randomized trial.
  • However, IV estimates indicated substantially larger effects with very wide confidence intervals.
  • This suggests reduced statistical precision compared to conventional methods.

Conclusions:

  • The limited statistical precision of IV analysis restricts its utility in studies of moderate size.
  • Even with a strong and plausible instrument, IV analysis may not be sufficiently precise for reliable conclusions in such settings.