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

Blinding01:11

Blinding

3.5K
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.
3.5K
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches01:23

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

197
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,...
197
Blind Procedures02:07

Blind Procedures

12.4K
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...
12.4K
Randomized Experiments01:13

Randomized Experiments

8.2K
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...
8.2K
Study Designs in Epidemiology01:20

Study Designs in Epidemiology

489
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...
489
What is an Experiment?01:12

What is an Experiment?

15.8K
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...
15.8K

You might also read

Related Articles

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

Sort by
Same author

The modelled impact of low traffic neighbourhoods (LTNs) on air pollution: findings from 5 schemes in London.

Environmental research·2026
Same author

Integrating genetic data with biological insight: A practical guide to cis-Mendelian randomization.

American journal of human genetics·2026
Same author

Assessing the Causal Effects of Environmental Tobacco Smoke Exposure: A meta-analytic Mendelian randomisation study.

Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco·2026
Same author

Extending the Use of Mendelian Randomisation With Non-Inherited Variants to Assess Socially Transmitted Parental Exposures Under Assortative Mating.

Genetic epidemiology·2026
Same author

Phosphodiesterase-5 Inhibition and Alzheimer's Disease Risk: A Mendelian Randomisation Study.

Aging cell·2025
Same author

The role of estimation in Mendelian randomization: should Mendelian randomization investigations provide estimates?

AJE advances : research in epidemiology·2025

Related Experiment Video

Updated: Oct 11, 2025

E-Patient Counseling Trial E-PACO: Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy
06:28

E-Patient Counseling Trial E-PACO: Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

Published on: August 1, 2019

8.5K

Does pre-notification increase questionnaire response rates: a randomised controlled trial nested within a systematic

Benjamin Woolf1,2,3, Phil Edwards4

  • 1Department of Psychological Science, University of Bristol, 5 Priory Road, Bristol, UK. Benjamin.woolf@bristol.ac.uk.

BMC Medical Research Methodology
|November 28, 2021
PubMed
Summary
This summary is machine-generated.

Pre-notification before requesting data from study authors did not improve response rates in this systematic review update. Further research is needed due to the study

Keywords:
Pre-notificationQuestionnaire responseRandomised controlled trials

More Related Videos

A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting
14:43

A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting

Published on: January 12, 2018

12.2K
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

14.7K

Related Experiment Videos

Last Updated: Oct 11, 2025

E-Patient Counseling Trial E-PACO: Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy
06:28

E-Patient Counseling Trial E-PACO: Computer Based Education versus Nurse Counseling for Patients to Prepare for Colonoscopy

Published on: August 1, 2019

8.5K
A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting
14:43

A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting

Published on: January 12, 2018

12.2K
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

14.7K

Area of Science:

  • Systematic review methodology
  • Research methodology
  • Meta-analysis

Background:

  • Missing outcome data in systematic reviews can introduce bias.
  • Contacting trial authors for missing data often results in low response rates.
  • Pre-notification strategies are explored to improve author communication and data retrieval.

Purpose of the Study:

  • To evaluate if pre-notification of an upcoming data request increases response rates from study authors.
  • To assess the impact of advance communication on author participation in systematic review updates.

Main Methods:

  • A randomized controlled trial nested within a systematic review update.
  • Study authors were randomized to receive pre-notification (1 day prior) or no pre-notification before a data request.
  • Response rate was defined as the proportion of authors who replied to the information request.

Main Results:

  • The response rate was 42.4% in the pre-notification group (14/33 authors) and 42.9% in the control group (18/42 authors).
  • No statistically significant difference in response rates was observed between the pre-notification and control groups (p=1).
  • No author complaints were received regarding the pre-notification method.

Conclusions:

  • Pre-notification did not demonstrate an increase in study author response rates for data requests.
  • The study's low statistical power limits generalizability to other contexts or populations.
  • Further investigation is required to determine the efficacy of pre-notification strategies in systematic reviews.