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Related Concept Videos

Randomized Experiments01:13

Randomized Experiments

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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
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Group Design02:01

Group Design

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The most basic experimental design involves two groups: the experimental group and the control group. The two groups are designed to be the same except for one difference— experimental manipulation. The experimental group gets the experimental manipulation—that is, the treatment or variable being tested—and the control group does not. Since experimental manipulation is the only difference between the experimental and control groups, we can be sure that any differences between...
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Blinding01:11

Blinding

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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.
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Random Sampling Method01:09

Random Sampling Method

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Sampling is a technique to select a portion (or subset) of the larger population and study that portion (the sample) to gain information about the population. Data are the result of sampling from a population. The sampling method ensures that samples are drawn without bias and accurately represent the population. Because measuring the entire population in a study is not practical, researchers use samples to represent the population of interest. Among the various sampling methods used by...
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Bioequivalence Experimental Study Designs: Completely Randomized and Randomized Block Designs01:20

Bioequivalence Experimental Study Designs: Completely Randomized and Randomized Block Designs

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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...
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Random and Systematic Errors01:20

Random and Systematic Errors

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Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be random or systematic. Random errors are observed due to the inconsistency or fluctuation in the measurement process, or variations in the quantity itself that is being measured. Such errors fluctuate from being greater than or less than the true value in repeated measurements. Consider a scientist measuring the length of an earthworm using a...
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Inverse Probability of Treatment Weighting Propensity Score using the Military Health System Data Repository and National Death Index
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Invited commentary: every good randomization deserves observation.

Daniel Westreich, Jessie K Edwards

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    |October 22, 2015
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    Summary
    This summary is machine-generated.

    Preexposure prophylaxis (PrEP) effectively prevents HIV transmission when taken daily. This study explores how well PrEP trial results apply to real-world use, considering adherence challenges.

    Keywords:
    HIVadherencecausal inferenceexternal validitygeneralizabilitypre-exposure prophylaxisrandomized trialstransportability

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    Area of Science:

    • Public Health
    • Epidemiology
    • Pharmacology

    Background:

    • Preexposure prophylaxis (PrEP) involves daily antiretroviral medication for HIV-negative individuals to prevent transmission.
    • The Partners PrEP Study provides data on PrEP efficacy in Kenya and Uganda.
    • Adherence significantly impacts intervention effectiveness, raising questions about trial generalizability.

    Purpose of the Study:

    • To estimate the efficacy of PrEP under conditions of perfect adherence.
    • To examine the generalizability of randomized trial findings to real-world settings.
    • To explore how adherence influences the transportability of PrEP intervention effects.

    Main Methods:

    • Analysis of data from the Partners PrEP Study (2008-2011).
    • Estimation of PrEP efficacy with perfect adherence.
    • Utilizing causal directed acyclic graphs to assess generalizability.

    Main Results:

    • PrEP demonstrated efficacy under perfect adherence conditions.
    • The study highlights the importance of adherence in determining real-world effectiveness.
    • Generalizability of trial findings depends on specific assumptions about adherence.

    Conclusions:

    • Findings from PrEP trials require careful consideration of adherence for real-world application.
    • Causal inference methods can help evaluate the transportability of trial results.
    • Understanding adherence is crucial for successful implementation of PrEP programs.