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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...
Bioequivalence Experimental Study Designs: Repeated Measures, Cross-Over, Carry-Over, and Latin Square Designs01:15

Bioequivalence Experimental Study Designs: Repeated Measures, Cross-Over, Carry-Over, and Latin Square Designs

Bioequivalence experimental study designs play a pivotal role in testing the effectiveness of various treatments. Key among these are the repeated measures, cross-over, carry-over, and Latin square designs. In the repeated measures design, each subject receives all treatments, allowing for temporal comparisons. This type of design is useful in reducing variability but requires careful planning to avoid bias.The cross-over design, an economical method, involves sequential administration of...
Bioequivalence Experimental Study Designs: Completely Randomized and Randomized Block Designs01:20

Bioequivalence Experimental Study Designs: Completely Randomized and Randomized Block Designs

Bioequivalence experimental study designs are crucial methodologies used in evaluating and comparing the bioavailability of different drug products. These designs are categorized into various types: completely randomized, randomized block, repeated measures, cross and carry-over, and Latin square designs.Completely randomized designs involve randomly allocating treatments to all subjects participating in the experiment. This allocation is achieved by assigning unique random numbers to subjects...
Observational Studies01:11

Observational Studies

Observational studies are a type of analytical study where researchers observe events without any interventions. In other words, the researcher does not influence the response variable or the experiment's outcome.
There are three types of observational studies – Prospective, retrospective, and cross-sectional.
Prospective Study
Prospective studies, also known as longitudinal or cohort studies, are carried out by collecting future data from groups sharing similar characteristics. One example of...
Study Designs in Epidemiology01:20

Study Designs in Epidemiology

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 case-control studies.
Blind Procedures02:07

Blind Procedures

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 child was...

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Related Experiment Video

Updated: May 8, 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

When ethics precludes randomization: put prospective, matched-pair observational studies to work.

Charles Joseph Kowalski

    Perspectives in Biology and Medicine
    |August 27, 2013
    PubMed
    Summary

    When randomized controlled trials (RCTs) face ethical barriers, prospective, matched-pair observational studies offer a rigorous alternative. These studies maintain methodological integrity, mitigating knowledge loss in clinical research.

    Related Experiment Videos

    Last Updated: May 8, 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

    Area of Science:

    • Clinical research methodology
    • Observational study design

    Background:

    • Randomized controlled trials (RCTs) are the gold standard but face ethical and practical limitations.
    • Ethical considerations can preclude randomization in certain clinical research scenarios.

    Purpose of the Study:

    • To propose an alternative to RCTs when randomization is not feasible.
    • To advocate for prospective, matched-pair observational studies as a viable ethical alternative.
    • To explore extending observational studies for continuous clinical knowledge accumulation.

    Main Methods:

    • Suggesting prospective, protocol-driven, matched-pair observational studies.
    • Emphasizing the maintenance of methodological rigor comparable to RCTs.
    • Proposing the extension of observational studies for real-world data gathering.

    Main Results:

    • Prospective, matched-pair observational studies can serve as a practical and ethical alternative to RCTs.
    • Maintaining methodological rigor mitigates potential epistemic losses from non-randomization.
    • Observational studies can be adapted for continuous knowledge accumulation.

    Conclusions:

    • Prospective, matched-pair observational studies are recommended when ethical issues prevent RCTs.
    • Methodological rigor is key to the validity of these observational studies.
    • The framework supports ongoing clinical knowledge generation in real-world settings.