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

Longitudinal Research02:20

Longitudinal Research

13.3K
Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may survey a group of individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again...
13.3K
Cardiomyopathy VII: Pre and Post Operative Nursing Management01:28

Cardiomyopathy VII: Pre and Post Operative Nursing Management

353
Patients with hypertrophic cardiomyopathy (HCM) and left ventricular outflow tract (LVOT) obstruction who remain symptomatic despite optimal medical therapy may undergo a septal myectomy (Morrow procedure). This procedure involves excising a portion of the hypertrophied septum below the aortic valve using a heart-lung machine to improve blood flow through the LVOT. Effective preoperative and postoperative nursing management ensures successful patient outcomes, minimizes complications, and...
353
Muscles that Move the Arm01:31

Muscles that Move the Arm

4.8K
Nine muscles are involved in arm movements. Two of these, the pectoralis major and latissimus dorsi, originate from the axial skeleton and are called axial muscles. The other seven originate from the scapula and are called the scapular muscles.
The pectoralis major has two origins. Its clavicular head originates on the medial half of the clavicle. In contrast, the sternocostal head originates on the costal cartilages of ribs 1-6, the sternum, and the aponeurosis of the external oblique of the...
4.8K
Nursing Interventions I: Taxonomy of Nursing Interventions01:03

Nursing Interventions I: Taxonomy of Nursing Interventions

3.9K
Nursing interventions are chosen as part of the planning process to achieve patient outcomes. Once nursing diagnoses are determined, the goals and outcomes are specified, then the nursing interventions are selected and individualized according to the patient's situation.
A nursing intervention is a treatment or action based on scientific concepts and knowledge from the nursing, behavioral, and physical sciences. Identifying and prioritizing nursing interventions based on the desired outcome...
3.9K
Nursing Interventions II: Selecting and Classifying the Nursing Interventions01:29

Nursing Interventions II: Selecting and Classifying the Nursing Interventions

3.3K
Creating and executing a nursing diagnosis helps nurses plan care and guide patient, family, and community interventions. They are developed based on a patient's physical evaluation and support measuring the outcomes. It is not recommended to select random interventions throughout the planning process. Instead, consider the following six essential factors when choosing interventions:
3.3K
Clinical Trials: Overview01:11

Clinical Trials: Overview

5.0K
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...
5.0K

You might also read

Related Articles

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

Sort by
Same author

Genital Inflammatory Responses in Women Living with HIV Randomized to Copper or Levonorgestrel Intrauterine Contraceptives: A secondary analysis of a randomized trial.

medRxiv : the preprint server for health sciences·2026
Same author

Recent progress of dendritic cell-derived exosomes in tumor immunotherapy.

Investigational new drugs·2026
Same author

Serum Biomarkers of Macrophage Activation and Incident CKD in People With and Without HIV: Findings From the MACS-WIHS Combined Cohort Study.

Open forum infectious diseases·2026
Same author

Examining Referral Pathways for Patients with Hematuria: A Real-World Retrospective Analysis.

Glomerular diseases·2026
Same author

The role and possible mechanism of intestinal fungi in the progression of chronic liver diseases.

NPJ biofilms and microbiomes·2026
Same author

HIV disease progression following WHO treat all guideline adoption among people enrolled in HIV care in Central Africa: A multistate analysis.

Annals of epidemiology·2026
Same journal

PROSPECTIVELY ESTIMATING THE AGE OF INITIATION OF E-CIGARETTES AMONG U.S. YOUTH: FINDINGS FROM THE POPULATION ASSESSMENT OF TOBACCO AND HEALTH (PATH) STUDY, 2013-2017.

Journal of biometrics & biostatistics·2021
Same journal

Simple Power and Sample Size Estimation for Non-Randomized Longitudinal Difference in Differences Studies.

Journal of biometrics & biostatistics·2019
Same journal

Deep Learning Methods for Predicting Disease Status Using Genomic Data.

Journal of biometrics & biostatistics·2019
Same journal

Methods for the Analysis of Missing Data in FMRI Studies.

Journal of biometrics & biostatistics·2019
Same journal

Methods for Analysis of Pre-Post Data in Clinical Research: A Comparison of Five Common Methods.

Journal of biometrics & biostatistics·2018
Same journal

Empirical Comparison of the Breslow Estimator and the Kalbfleisch Prentice Estimator for Survival Functions.

Journal of biometrics & biostatistics·2018
See all related articles

Related Experiment Video

Updated: Feb 3, 2026

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment
08:36

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment

Published on: April 19, 2024

1.2K

Power Estimation in Planning Randomized Two-Arm Pre-Post Intervention Trials with Repeated Longitudinal Outcomes.

Yirui Hu1, Donald R Hoover2

  • 1Biomedical and Translational Informatics, Geisinger, Danville, 17821, USA.

Journal of Biometrics & Biostatistics
|November 3, 2018
PubMed
Summary
This summary is machine-generated.

Estimating intervention effects in clinical trials requires accurate power calculations. This study shows that the commonly used compound symmetry correlation structure often fails, leading to inaccurate power estimations for longitudinal data.

Keywords:
Compound symmetryGeneralized least squaresMixed modelOptimal allocationPower and sample size estimationPre-post interventional studyToeplitz correlation

More Related Videos

Author Spotlight: Regenerative Peripheral Nerve Interface (RPNI) Surgery in Postamputation Pain Management
03:53

Author Spotlight: Regenerative Peripheral Nerve Interface (RPNI) Surgery in Postamputation Pain Management

Published on: March 15, 2024

2.9K
Author Spotlight: Advancements and Challenges in Surgical Treatments for Postamputation Pain
03:26

Author Spotlight: Advancements and Challenges in Surgical Treatments for Postamputation Pain

Published on: March 8, 2024

3.5K

Related Experiment Videos

Last Updated: Feb 3, 2026

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment
08:36

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment

Published on: April 19, 2024

1.2K
Author Spotlight: Regenerative Peripheral Nerve Interface (RPNI) Surgery in Postamputation Pain Management
03:53

Author Spotlight: Regenerative Peripheral Nerve Interface (RPNI) Surgery in Postamputation Pain Management

Published on: March 15, 2024

2.9K
Author Spotlight: Advancements and Challenges in Surgical Treatments for Postamputation Pain
03:26

Author Spotlight: Advancements and Challenges in Surgical Treatments for Postamputation Pain

Published on: March 8, 2024

3.5K

Area of Science:

  • Biostatistics
  • Clinical Trial Design
  • Longitudinal Data Analysis

Background:

  • Intervention effects are typically estimated using Generalized Least Squares (GLS) models in clinical trials with repeated longitudinal measurements.
  • Power estimation for these studies is challenging due to a lack of GLS-based approaches and normative data.

Purpose of the Study:

  • To derive Generalized Least Squares (GLS) variance for intervention effects.
  • To develop simple power formulas based on the compound symmetry correlation structure.
  • To investigate optimal pre-post allocation for maximizing statistical power.

Main Methods:

  • Derived GLS variance of the intervention effect.
  • Developed power formulas assuming compound symmetry correlation.
  • Investigated optimal pre-post allocation for variance minimization.

Main Results:

  • Empirical analysis of nursing home and HIV patient data revealed Toeplitz correlation structures, differing from compound symmetry.
  • Power calculations using Toeplitz structures showed that one pre-intervention measure often maximized power, contrary to compound symmetry assumptions.
  • Approximating Toeplitz structures with compound symmetry led to overestimation of power.

Conclusions:

  • The compound symmetry correlation structure, while simplifying power estimation, frequently does not reflect the actual correlation in repeated measures.
  • Using compound symmetry to approximate unknown Toeplitz correlations can lead to significant underestimation of the variance of the intervention effect estimate.
  • Accurate power estimation requires accounting for the specific correlation structure of longitudinal data, such as the decline in correlation over time.