This document provides an overview of randomized control trials (RCTs). It discusses key aspects of RCT design including types of RCTs based on interventions evaluated (explanatory vs pragmatic), participants exposed (parallel vs crossover), number of participants (from n-of-1 trials to mega-trials), blinding of investigators/participants, and accounting for participant preferences. It also covers randomization techniques and their advantages, sample size calculations, and references for further information.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
Methods of randomisation in clinical trialsAmy Mehaboob
Randomization is the process by which allocation of subjects to treatment groups is done by chance, without the ability to predict who is in what group. A randomized clinical trial is a clinical trial in which participants are randomly assigned to separate groups that compare different treatments.
Randomized trials are gold standard of study designs because the potential for bias (selection into treatment groups) is avoided.
This document includes the purpose, types, advantages and disadvantages of each type of randomisation.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
Methods of randomisation in clinical trialsAmy Mehaboob
Randomization is the process by which allocation of subjects to treatment groups is done by chance, without the ability to predict who is in what group. A randomized clinical trial is a clinical trial in which participants are randomly assigned to separate groups that compare different treatments.
Randomized trials are gold standard of study designs because the potential for bias (selection into treatment groups) is avoided.
This document includes the purpose, types, advantages and disadvantages of each type of randomisation.
Randomization is the process by which allocation of subjects to treatment groups is done by chance, without the ability to predict who is in what group. It is done in clinical trials. This presentation describes the methods of randmization used in clinical trials.
Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
NEED FOR RESEARCH
Research is a systemic process of collecting and analyzing information to increase the understanding of the phenomenon under study.
It strengthens pharmacist-provided services, builds the evidence base for developing and commissioning new services, improves patient care and contributes to health service knowledge.
Phase I studies: Are done on healthy volunteers who agree to take the study drug to help the doctors determine how safe the drug is and if there are any side effects. Usually a small number of subjects (20-100) participate in Phase I studies. Approximately 70% of new drugs will pass this phase.
Phase II studies: Measure the effect of the new drug in patients with the disease or disorder to be treated. The main purpose is to determine safety and effectiveness of the new drug. Usually several hundred patients participate. These studies are usually “Double-blinded, randomized and controlled”.
Phase III studies: also use patients with the disorder to be treated by the new drug. These studies are done to gain a more thorough understanding of the effectiveness, benefits and side effects of the study drug.
NEED FOR DESIGN OF EXPERIMENTS
Design of experiments (DOE) is defined as a branch of applied statistics that deals with planning, conducting, analyzing, and interpreting controlled tests to evaluate the factors that control the value of a parameter or group of parameters.
DOE is a powerful data collection and analysis tool that can be used in a variety of experimental situations.
1. PRE-EXPERIMENTAL DESIGN
In pre-experimental research design, either a group or various dependent groups are observed for the effect of the application of an independent variable which is presumed to cause change.
It is the simplest form of experimental research design and is treated with no control group
2. TRUE EXPERIMENTAL DESIGN
The true experimental research design relies on statistical analysis to approve or disprove a hypothesis. It is the most accurate type of experimental design and may be carried out with or without a pretest on at least 2 randomly assigned dependent subjects.
The true experimental research design must contain a control group, a variable that can be manipulated by the researcher, and the distribution must be random.
3. QUASI EXPERIMENTAL DESIGN
The word "quasi" means partial, half, or pseudo. Therefore, the quasi-experimental research bearing a resemblance to the true experimental research, but not the same. In quasi-experiments, the participants are not randomly assigned, and as such, they are used in settings where randomization is difficult or impossible.
This is very common in educational research, where administrators are unwilling to allow the random selection of students for experimental samples.
PLAGIARISM
The word Plagiarism is derived from the Latin word Plagiarius, which means abducting, kidnapping, seducing, or plundering.
Randomization is the process by which allocation of subjects to treatment groups is done by chance, without the ability to predict who is in what group. It is done in clinical trials. This presentation describes the methods of randmization used in clinical trials.
Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
NEED FOR RESEARCH
Research is a systemic process of collecting and analyzing information to increase the understanding of the phenomenon under study.
It strengthens pharmacist-provided services, builds the evidence base for developing and commissioning new services, improves patient care and contributes to health service knowledge.
Phase I studies: Are done on healthy volunteers who agree to take the study drug to help the doctors determine how safe the drug is and if there are any side effects. Usually a small number of subjects (20-100) participate in Phase I studies. Approximately 70% of new drugs will pass this phase.
Phase II studies: Measure the effect of the new drug in patients with the disease or disorder to be treated. The main purpose is to determine safety and effectiveness of the new drug. Usually several hundred patients participate. These studies are usually “Double-blinded, randomized and controlled”.
Phase III studies: also use patients with the disorder to be treated by the new drug. These studies are done to gain a more thorough understanding of the effectiveness, benefits and side effects of the study drug.
NEED FOR DESIGN OF EXPERIMENTS
Design of experiments (DOE) is defined as a branch of applied statistics that deals with planning, conducting, analyzing, and interpreting controlled tests to evaluate the factors that control the value of a parameter or group of parameters.
DOE is a powerful data collection and analysis tool that can be used in a variety of experimental situations.
1. PRE-EXPERIMENTAL DESIGN
In pre-experimental research design, either a group or various dependent groups are observed for the effect of the application of an independent variable which is presumed to cause change.
It is the simplest form of experimental research design and is treated with no control group
2. TRUE EXPERIMENTAL DESIGN
The true experimental research design relies on statistical analysis to approve or disprove a hypothesis. It is the most accurate type of experimental design and may be carried out with or without a pretest on at least 2 randomly assigned dependent subjects.
The true experimental research design must contain a control group, a variable that can be manipulated by the researcher, and the distribution must be random.
3. QUASI EXPERIMENTAL DESIGN
The word "quasi" means partial, half, or pseudo. Therefore, the quasi-experimental research bearing a resemblance to the true experimental research, but not the same. In quasi-experiments, the participants are not randomly assigned, and as such, they are used in settings where randomization is difficult or impossible.
This is very common in educational research, where administrators are unwilling to allow the random selection of students for experimental samples.
PLAGIARISM
The word Plagiarism is derived from the Latin word Plagiarius, which means abducting, kidnapping, seducing, or plundering.
Steps in conducting a RCT
1. Drawing up a protocol
2. Selecting Reference & Experimental population
3. Randomization
4. Manipulation or Intervention
5. Follow up
6. Assessment of outcome
1. Drawing up a protocol
Aims and objectives of the study
Questions to be answered
Criteria for the selection of study and control groups
Size of the sample & allocation of subjects in both groups
Treatment to be applied - when, where, how
Standardization of working procedures and
Schedules as well as responsibilities of persons involved in the trial up to the stage of evaluation of outcome of the study.
2. Selecting Reference and Experimental Populations
Reference or target population - Population to which the findings of the trial, if found successful, are expected to be applicable (Eg: drugs, vaccines, etc.)
Experimental or Study population
Derived from the Reference population
Has same characteristics as the Reference population
Actual population that participates in the experimental study
Must give informed consent - Should be qualified or eligible for the trial
3. Randomization
Heart of the control trial
Procedure:
Participants are allocated into study and control groups
Eliminates bias and allows comparability
By random allocation every individual gets an equal chance for being allocated in to either groups.
4. Manipulation/ Intervention
Having formed the study and control group, the next step is to intervene or manipulate the study (experimental) group by deliberate application or withdrawal or reduction of a suspected causal factor
Eg: Drug, Vaccine, Dietary component, a habit
5. Follow up
Implies examination of the experimental and control group subjects at defined intervals of time in a standard manner, with equal intensity, under the same given circumstances in the same time frame till final assessment of outcome.
Attrition:
Inevitable losses to follow up (death, migration, loss of interest)
6. Assessment
a. Positive results:
Reduced incidence or severity of disease
Reduced cost to health service
Appropriate outcome in the study
b. Negative results:
Increased severity or frequency of side effects
Complications
Deaths
BIAS:
Any systematic error in the determination of association and outcome.
Bias may arise from errors of assessment of outcome due to human element
Subjective bias
Observer bias
Evaluation bias
1. Subjective Bias:
Participants, subjectively feel better or report improvement if they knew they were receiving a new form of treatment. This is known as “Subject variation”.
2. Observer Bias:
Investigator measuring the outcome of a therapeutic trial may be influenced if he knows beforehand the particular procedure or therapy to which the patient has been subjected.
3. Evaluation Bias:
Investigator may subconsciously give a favorable report of the outcome of the trial.
Blinding:
1. Single Blind Trial: Participant
2. Double Blind: Partcipant + Investigator
3. Triple Blind: Participant + Investigator + Data Analyzer
Randomized Control Trials
Enigma of Blinding Unraveled
Introduction
RCT
Steps in a RCT
Allocation Concealment
Bias in RCT
Phases in RCT
Types of RCT
Study Designs of RCT
Blinding
Methods of Blinding in different trials
Assessment of Blinding
Un-blinding
Current Scenario of Blinding
CONSORT
Conclusion
References
RANDOMIZED CONTROL trials
an assessment method
questions validity and applicability of many preventive and therapeutic procedures
reference Park's Preventive and social medicine
Health system in the perspectives of health economicsBPKIHS
Here is the slide on Health system in the perspectives of health economics. The content of this presentation doesn't belong to me. They are copied from several literature and internet
Here is the slide on Healthcare economic evaluation. The content of this presentation doesn't belong to me. They are copied from several literature and internet
Outline:
Introduction
Epidemiologic Determinants
Mode of transmission
Burden of Hepatitis-B
Prevention and treatment
Challenges
Recent Advances in Hepatitis B research
Strategies
References
Maternal and Neonatal morbidity and MortalityBPKIHS
It deals with:
Introduction
International Perspectives
National Status
Complication during Pregnancy, Childbirth, Postpartum period including Neonatal Problems
Causes of Maternal and neonatal mortality
Framework of determinants of maternal mortality
Three delay model
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
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4. Randomized Control Trial
• It is a trial in which subjects are randomly assigned to one of two groups:
• Experimental group receiving the intervention
• Comparison group or control receiving an alternative/conventional treatment
• The two groups followed up to see any differences in outcome.
• The results and subsequent analysis of the trial:
• Used to assess the effectiveness of the intervention (treatment, procedure, or
service does patients more good than harm)
• Used to determine whether a cause-effect relation exists between the
intervention and the outcome.
6. Types of RCT
• According to the aspects of the interventions they evaluate
• Explanatory and pragmatic trials
• Efficacy and effectiveness trials
• Phase I, II, and III trials
• According to how the participants are exposed to the interventions
• Parallel trials
• Crossover trials
• Trials with factorial design
7. Types of RCT
• According to the number of participants
• From n-of-1 to mega-trials
• Fixed size
• Sequential trials
• According to whether the investigators and participants know
which intervention is being assessed
• Open trials
• Single blind trials
• Double blind trials
• Triple and quadruple-blind trials
8. • According to whether the preferences of non-randomised
individuals and participants are taken into account
• Zelen's design
• Comprehensive cohort design
• Wennberg's design
9. RCT according to the aspects of the
interventions
Explanatory trials
• Address whether or not an intervention works. If the intervention
works, then these trials attempt to establish how such intervention
works.
• It tend to use placebos as controls, fixed regimens (that is, 20 mg by
mouth every 6 hours), long washout periods (if patients have been
taking diuretics, for instance, those drugs will be stopped for a
sufficient period of time to ensure that they are ‘washed out’ of their
bodies), intention to treat analysis, and focus on ‘hard’ outcomes (that
is, blood pressure recorded at specific times after a detailed and
standardised process).
10. RCT according to the aspects of the
interventions
Pragmatic trials (aka. management trials):
• Designed not only to determine whether the intervention works, but also to
describe all the consequences of its use, good and bad, under circumstances
mimicking clinical practice.
• To achieve this, pragmatic studies tend to use more lax criteria to include
participants with heterogeneous characteristics, similar to those seen by
clinicians in their daily practice.
• In addition to the more lax inclusion criteria, pragmatic trials tend to use active
controls (that is, the new antihypertensive drug vs a b-blocker), flexible
regimens (that is, 20 mg orally every 6 hours, reducing or increasing the dose by
5 mg according to the degree of blood pressure control and adverse effects), and
analysis of the patients who received the interventions. Pragmatic trials do not
preclude the use of ‘soft’ outcome measures, such as measures of sexual
function or quality of life.
12. RCT according to the aspects of the
interventions
Efficacy trial
• Efficacy refers to whether an intervention works in people who receive it.
• Trials designed to establish efficacy
• Tend to be explanatory trials, because they are designed to yield a ‘clean’
evaluation of the effects of the intervention.
• Investigators are not so interested in finding out how the intervention
works. Instead, their main goal is to include participants who will follow
their instructions and who will receive the intervention.
13. RCT according to the aspects of the
interventions
Effectiveness trial
• Effectiveness refers to whether an intervention works in people to whom it has
been offered.
• Tend to be pragmatic, because they try to evaluate the effects of the
intervention in circumstances similar to those found by clinicians in their daily
practice.
• The design of effectiveness trials is usually simpler than the design of efficacy
trials, because effectiveness trials tend to follow lax inclusion criteria, include
flexible regimens, and allow participants to accept or reject the interventions
offered to them.
• Typically, effectiveness trials evaluate interventions with proven efficacy
when they are offered to a heterogeneous group of people under ordinary
clinical circumstances.
16. • Parallel trial:
RCT
according
to how the
participants
are exposed
to the
interventions
This design is
appropriate for chronic
conditions that are
stable over time and for
interventions that last a
short time.
A drawback of the
factorial design is the
concern over potential
drug interactions;
however, this design
also allows for the
determination of
synergies between two
This design is simple
and eliminates the
potential for drug
interaction.
17. RCT according to the number of participants
n-of-1 trials
• Aka. individual patient trials.
• Basically, they are crossover trials in which one participant receives
the experimental and the control interventions, in pairs, on multiple
occasions and in random order.
• These trials provide individual, rather than generalizable, results.
• They can be very useful when it is not clear whether a treatment will
help a particular patient.
18. Mega-trial
• Term is being used increasingly to describe RCTs with a simple design
(usually very pragmatic) which include thousands of patients and limited
data collection.
• Usually, these trials require the participation of many investigators
(sometimes hundreds of them) from multiple centers and from different
countries.
• The main purpose is to obtain ‘increased statistical power’ and to achieve
wider generalizability.
• Its main aim is to increase the chances of finding a difference between two
or more interventions, if such a difference exists.
19. • A multicenter research trial is a clinical trial conducted at more than
one medical center or clinic. Most large clinical trials, particularly
Phase III trials, are conducted at several clinical research centers.
• Benefits:
• Larger number of participants
• Different geographic locations
• Possibility of inclusion of a wider range of population groups
• Ability to compare results among centers
• All of which increase the generalizability of the study.
20. A sequential trial
• It is a study with parallel design in which the number of participants is
not specified by the investigators beforehand. Instead, the investigators
continue recruiting participants until a clear benefit of one of the
interventions is observed, or until they are convinced that there are no
important differences between the interventions.
• These trials allow a more efficient use of resources than trials with
fixed numbers of participants, but they depend on the principal
outcome being measured relatively soon after trial entry.
21. Fixed size trial
• The investigators establish deductively the number of participants that
they will include.
• This number can be decided arbitrarily or can be calculated using
statistical methods.
• The main goal of using statistical methods to calculate the sample size
is to maximize the chance of detecting a statistically and clinically
significant difference between the interventions when a difference
really exists
22. RCT according to whether the investigators and
participants know which intervention is being
assessed
27. Types of RCT
• Prophylactic Trials
• Evaluate the efficacy of intervention that is designed to prevent disease
• Example: Vaccine trials, patient education, screening, vitamin supplement
• Curative Trials
• Evaluate the efficacy of the curative drugs or intervention designed to manage
or mitigate the sign and symptoms of disease
• Example: Arthritis, Hypertension drug trials
28. RCT on the basis of Hypothesis
• Superiority studies
• It aims to show that a new drug is more effective than the comparative
treatment (placebo or current best treatment)
• Non Inferiority studies
• It is designed to prove that two drugs have the same clinical benefit.
• Equivalence studies
• It aims to show that the effect of a new treatment cannot be said to be
significantly weaker than that of the current treatment.
29. Features of a well designed RCT
• The sample to be studied will be appropriate to the hypothesis being
tested so that any results are appropriately generalizable. The study
will recruit sufficient patients to allow it to have a high probability of
detecting a clinically important difference between treatments if a
difference truly exists.
• There will be effective (concealed) randomization of the subjects to
the intervention/control groups (to eliminate selection bias and
minimize confounding variables).
• Both groups will be treated identically in all respects except for the
intervention being tested and to this end patients and investigators will
ideally be blinded to which group an individual is assigned.
30. Features of a well designed RCT
• The investigator assessing outcome will be blinded to treatment
allocation.
• Patients are analyzed within the group to which they were allocated,
irrespective of whether they experienced the intended intervention
(intention to treat analysis).
• Analysis focuses on testing the research question that initially led to
the trial (that is, according to the a priori hypothesis being tested),
rather than “trawling” to find a significant difference.
31. Randomization in RCT
Advantages
• Eliminates selection bias, balancing both known and unknown prognostic
factors, in the assignment of treatments.
• Random assignment permits the use of probability theory to express the
likelihood that any difference in outcome between intervention groups
merely reflects chance
• Random allocation, in some situations, facilitates blinding the identity of
treatments to the investigators, participants, and evaluators, possibly by use
of a placebo, which reduces bias after assignment of treatments
Confidently
attribute to cause
and effect
32. Randomization in RCT
• Randomization tends to distribute potential confounders similarly among
exposure groups, which removes this necessary precondition.
33. Randomization in RCT
Successful randomization in practice depends on three interrelated
aspects:
• Adequate generation of an unpredictable allocation sequence
• Concealment of that sequence until assignment occurs
• Implementation- Who generated random allocation sequence and
who enrolled participants
34. Randomization in RCT
• Several types of Randomization present in RCT but choice depends on
two goals:
• Balance : There should be balance of measured and unmeasured
characteristics between intervention and control group.
• Unpredictability: There should not be no predictability for enrollment
of intervention and control group.
35. Types of Randomization
• Simple Randomization
• Simple (or unrestricted) randomization is tantamount to flipping a coin.
• Every subject has an equal chance of being assigned to either group, and
all
assignments are independent of one another.
• Simple randomization thus maximizes unpredictability: the sequence
of past assignments provides no clue about the group to which the next
patient is likely to be assigned
• Possibility of chance imbalances, particularly with small sample sizes.
36. Types of Randomization
• Restricted randomization
• It refers to the use of another procedure along with random assignment
in order to promote balance in the sizes or composition of study groups.
37. Types of Randomization
• Block Randomization:
• Block randomization, the most common form of restricted
randomization, involves first grouping study subjects into sets, or blocks.
• Within each block, an equal number of subjects is then randomly
assigned to each treatment group.
• Block randomization gives priority to keeping the sizes of treatment
groups balanced. However, it does so at the expense of unpredictability.
• One way to help prevent corruption of block randomization is to use
larger block sizes.
38. Types of Randomization
Stratified Randomization
• It guarantee that a strong potential confounding factor will be
balanced between groups.
• Each level on the confounding factor becomes a stratum, and
randomization is carried out separately within each stratum.
• Block randomization (or some other form of restricted randomization)
must be used within each stratum to assure that the ratio of
experimental to control subjects is equal across strata.