This presentation is for educational purpose only. I do not own the rights to written material or pictures or illustrations used.
This is being uploaded for students who are in search of, or trying to understand how a quasi-experimental research design should look like.
Simple slide show about research designs especially made for students working with Science Investigatory Projects. This also helpful for students who are first timer working with research.
This presentation is for educational purpose only. I do not own the rights to written material or pictures or illustrations used.
This is being uploaded for students who are in search of, or trying to understand how a quasi-experimental research design should look like.
Simple slide show about research designs especially made for students working with Science Investigatory Projects. This also helpful for students who are first timer working with research.
Experimental Research Design (True, Quasi and Pre Experimental Design)Alam Nuzhathalam
Experimental Research Design., Introduction, Definition, Characteristics and Classification (True Experimental Research Design, Quasi Experimental Research Design and Pre Experimental Research Design)..
Research Design: single subject design -
History of studying the individual
Single subject research
Features of single subject designs
Reversal designs
Multiple baseline designs
Data analysis in single subject research
Advantages of single subject research
Disadvantages of single subject research
simplest way of explanation from a smart study.Sample techniques used in sampling. there are two types of techniques used in the process of sampling such as probability sampling and non probability sampling and here i have explained only Non- probability sampling.
In this ppt the viewer will able to know about Types of Experimental Design. During the research design what kind of experimental design is applicable? Why experimental design needed in experimental research. Experimental research is research conducted with a scientific approach using two sets of variables. The first set acts as a constant, which you use to measure the differences of the second set. (Example: Temperature & Time in reactor)
Portion explained:
1. Definition of Experimental research
2. Situations to conduct Experimental Research
3. Types of experimental research design
4. Pre-experimental research design
5. True experimental research design
6. Quasi-experimental research design
7. Advantages of experimental research
Experimental Research Design (True, Quasi and Pre Experimental Design)Alam Nuzhathalam
Experimental Research Design., Introduction, Definition, Characteristics and Classification (True Experimental Research Design, Quasi Experimental Research Design and Pre Experimental Research Design)..
Research Design: single subject design -
History of studying the individual
Single subject research
Features of single subject designs
Reversal designs
Multiple baseline designs
Data analysis in single subject research
Advantages of single subject research
Disadvantages of single subject research
simplest way of explanation from a smart study.Sample techniques used in sampling. there are two types of techniques used in the process of sampling such as probability sampling and non probability sampling and here i have explained only Non- probability sampling.
In this ppt the viewer will able to know about Types of Experimental Design. During the research design what kind of experimental design is applicable? Why experimental design needed in experimental research. Experimental research is research conducted with a scientific approach using two sets of variables. The first set acts as a constant, which you use to measure the differences of the second set. (Example: Temperature & Time in reactor)
Portion explained:
1. Definition of Experimental research
2. Situations to conduct Experimental Research
3. Types of experimental research design
4. Pre-experimental research design
5. True experimental research design
6. Quasi-experimental research design
7. Advantages of experimental research
A Research design is the framework or guide used for the planning, implementation and analysis of a study. It is a systematic plan of what is to be done, how it will be done and how the data will be analyzed
Factors Associated with Anemia among Pregnant Women of Underprivileged Ethnic...Prabesh Ghimire
Abstract
Background. This study aims at determining the factors associated with anemia among pregnant women of underprivileged ethnic groups attending antenatal care at the provincial level hospital of Province 2. Methods. A hospital-based cross-sectional study was carried out in Janakpur Provincial Hospital of Province 2, Southern Nepal. 287 pregnant women from underprivileged ethnic groups attending antenatal care were selected and interviewed. Face-to-face interviews using a structured questionnaire were undertaken. Anemia status was assessed based on hemoglobin levels determined at the hospital’s laboratory. Bivariate and multiple logistic regression analyses were used to identify the factors associated with anemia. Analyses were performed using IBM SPSS version 23 software. Results. The overall anemia prevalence in the study population was 66.9% (95% CI, 61.1–72.3). The women from most underprivileged ethnic groups (Terai Dalit, Terai Janajati, and Muslims) were twice more likely to be anemic than Madhesi women. Similarly, women having education lower than secondary level were about 3 times more likely to be anemic compared to those with secondary level or higher education. Women who had not completed four antenatal visits were twice more likely to be anemic than those completing all four visits. The odds of anemia were three times higher among pregnant women who had not taken deworming medication compared to their counterparts. Furthermore, women with inadequate dietary diversity were four times more likely to be anemic compared to women having adequate dietary diversity. Conclusions. The prevalence of anemia is a severe public health problem among pregnant women of underprivileged ethnic groups in Province 2. Being Dalit, Janajati, and Muslim, having lower education, less frequent antenatal visits, not receiving deworming medication, and having inadequate dietary diversity are found to be the significant factors. The present study highlights the need of improving the frequency of antenatal visits and coverage of deworming program in ethnic populations. Furthermore, promoting a dietary diversity at the household level would help lower the prevalence of anemia. The study findings also imply that the nutrition interventions to control anemia must target and reach pregnant women from the most-marginalized ethnic groups and those with lower education
Factors Associated with Enrolment of Households in Nepal’s National Health In...Prabesh Ghimire
Abstract
Background: Nepal has made remarkable efforts towards social health protection over the past several years. In 2016, the Government of Nepal introduced a National Health Insurance Program (NHIP) with an aim to ensure equitable and universal access to healthcare by all Nepalese citizens. Following the first year of operation, the scheme has covered 5 percent of its target population. There are wider concerns regarding the capacity of NHIP to achieve adequate population coverage and remain viable. In this context, this study aimed to identify the factors associated with enrolment of households in the NHIP.
Methods: A cross-sectional household survey using face to face interview was carried out in 2 Palikas (municipalities) of Ilam district. 570 households were studied by recruiting equal number of NHIP enrolled and non-enrolled households. We used Pearson’s chi-square test and binary logistic regression to identify the factors associated with household’s enrolment in NHIP. All statistical analyses were performed using IBM SPSS version 23 software.
Results: Enrolment of households in NHIP was found to be associated with ethnicity, socio-economic status, past experience of acute illness in family and presence of chronic illness. The households that belonged to higher socio-economic status were about 4 times more likely to enrol in the scheme. It was also observed that households from privileged ethnic groups such as Brahmin, Chhetri, Gurung, and Newar were 1.7 times more likely to enrol in NHIP compared to those from underprivileged ethnic groups such as janajatis (indigenous people) and dalits (the oppressed). The households with illness experience in 3 months preceding the survey were about 1.5 times more likely to enrol in NHIP compared to households that did not have such experience. Similarly, households in which at least one of the members was chronically ill were 1.8 times more likely to enrol compared to households with no chronic illness.
Conclusion: Belonging to the privileged ethnic group, having a higher socio-economic status, experiencing an acute illness and presence of chronically ill member in the family are the factors associated with enrolment of households in NHIP. This study revealed gaps in enrolment between rich-poor households and privileged-underprivileged ethnic groups. Extension of health insurance coverage to poor and marginalized households is therefore needed to increase equity and accelerate the pace towards achieving universal health coverage.
Recent Advances in Evidence Based Public Health PracticePrabesh Ghimire
This product is the result of compilation from various sources. I acknowledge all direct and indirect sources although they have not been mentioned explicitly in the document.
Observational analytical study: Cross-sectional, Case-control and Cohort stu...Prabesh Ghimire
This presentation provides overview of three observational analytical studies: cross-sectional study design, case-control study design and cohort study design
Development of test instruments
Includes information about:
Methods of collecting information
Interview techniques and tools
Observation: concept and observation checklist
This is the product of compilation from various sources. I would like to acknowledge all direct and indirect sources although they have not been mentioned explicitly within the document.
This product is the result of compilation from various sources. I would like to acknowledge all direct and indirect sources, although they have not been explicitly mentioned within the document.
This product is the result of compilation from various sources. I acknowledge all direct and indirect sources although they have not been mentioned explicitly in the document.
New Organogram of Nepalese Health System (Please check the updated slides on ...Prabesh Ghimire
This slide has been updated to accommodate the recent changes. Please check the following link for the updated presentation:
https://www.slideshare.net/PrabeshGhimire/organogram-organization-structure-of-nepalese-health-system-updated-nov-2021
Bilateral and Multilateral Organizations in NepalPrabesh Ghimire
Declaration: The materials incorporated in this document have come from variety of sources and compiler bears no responsibilities for any information contained herein. The compiler acknowledges all the sources although references have not been explicitly cited for all the contents in this document.
Declaration: The materials incorporated in this document have come from variety of sources and compiler bears no responsibilities for any information contained herein. The compiler acknowledges all the sources although references have not been explicitly cited for all the contents in this document.
International Non Government Organizations (INGOs) in NepalPrabesh Ghimire
Declaration: The materials incorporated in this document have come from variety of sources and compiler bears no responsibilities for any information contained herein. The compiler acknowledges all the sources although references have not been explicitly cited for all the contents in this document.
CHAPTER 1 SEMESTER V - ROLE OF PEADIATRIC NURSE.pdfSachin Sharma
Pediatric nurses play a vital role in the health and well-being of children. Their responsibilities are wide-ranging, and their objectives can be categorized into several key areas:
1. Direct Patient Care:
Objective: Provide comprehensive and compassionate care to infants, children, and adolescents in various healthcare settings (hospitals, clinics, etc.).
This includes tasks like:
Monitoring vital signs and physical condition.
Administering medications and treatments.
Performing procedures as directed by doctors.
Assisting with daily living activities (bathing, feeding).
Providing emotional support and pain management.
2. Health Promotion and Education:
Objective: Promote healthy behaviors and educate children, families, and communities about preventive healthcare.
This includes tasks like:
Administering vaccinations.
Providing education on nutrition, hygiene, and development.
Offering breastfeeding and childbirth support.
Counseling families on safety and injury prevention.
3. Collaboration and Advocacy:
Objective: Collaborate effectively with doctors, social workers, therapists, and other healthcare professionals to ensure coordinated care for children.
Objective: Advocate for the rights and best interests of their patients, especially when children cannot speak for themselves.
This includes tasks like:
Communicating effectively with healthcare teams.
Identifying and addressing potential risks to child welfare.
Educating families about their child's condition and treatment options.
4. Professional Development and Research:
Objective: Stay up-to-date on the latest advancements in pediatric healthcare through continuing education and research.
Objective: Contribute to improving the quality of care for children by participating in research initiatives.
This includes tasks like:
Attending workshops and conferences on pediatric nursing.
Participating in clinical trials related to child health.
Implementing evidence-based practices into their daily routines.
By fulfilling these objectives, pediatric nurses play a crucial role in ensuring the optimal health and well-being of children throughout all stages of their development.
Navigating the Health Insurance Market_ Understanding Trends and Options.pdfEnterprise Wired
From navigating policy options to staying informed about industry trends, this comprehensive guide explores everything you need to know about the health insurance market.
Struggling with intense fears that disrupt your life? At Renew Life Hypnosis, we offer specialized hypnosis to overcome fear. Phobias are exaggerated fears, often stemming from past traumas or learned behaviors. Hypnotherapy addresses these deep-seated fears by accessing the subconscious mind, helping you change your reactions to phobic triggers. Our expert therapists guide you into a state of deep relaxation, allowing you to transform your responses and reduce anxiety. Experience increased confidence and freedom from phobias with our personalized approach. Ready to live a fear-free life? Visit us at Renew Life Hypnosis..
QA Paediatric dentistry department, Hospital Melaka 2020Azreen Aj
QA study - To improve the 6th monthly recall rate post-comprehensive dental treatment under general anaesthesia in paediatric dentistry department, Hospital Melaka
The dimensions of healthcare quality refer to various attributes or aspects that define the standard of healthcare services. These dimensions are used to evaluate, measure, and improve the quality of care provided to patients. A comprehensive understanding of these dimensions ensures that healthcare systems can address various aspects of patient care effectively and holistically. Dimensions of Healthcare Quality and Performance of care include the following; Appropriateness, Availability, Competence, Continuity, Effectiveness, Efficiency, Efficacy, Prevention, Respect and Care, Safety as well as Timeliness.
Leading the Way in Nephrology: Dr. David Greene's Work with Stem Cells for Ki...Dr. David Greene Arizona
As we watch Dr. Greene's continued efforts and research in Arizona, it's clear that stem cell therapy holds a promising key to unlocking new doors in the treatment of kidney disease. With each study and trial, we step closer to a world where kidney disease is no longer a life sentence but a treatable condition, thanks to pioneers like Dr. David Greene.
India Clinical Trials Market: Industry Size and Growth Trends [2030] Analyzed...Kumar Satyam
According to TechSci Research report, "India Clinical Trials Market- By Region, Competition, Forecast & Opportunities, 2030F," the India Clinical Trials Market was valued at USD 2.05 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 8.64% through 2030. The market is driven by a variety of factors, making India an attractive destination for pharmaceutical companies and researchers. India's vast and diverse patient population, cost-effective operational environment, and a large pool of skilled medical professionals contribute significantly to the market's growth. Additionally, increasing government support in streamlining regulations and the growing prevalence of lifestyle diseases further propel the clinical trials market.
Growing Prevalence of Lifestyle Diseases
The rising incidence of lifestyle diseases such as diabetes, cardiovascular diseases, and cancer is a major trend driving the clinical trials market in India. These conditions necessitate the development and testing of new treatment methods, creating a robust demand for clinical trials. The increasing burden of these diseases highlights the need for innovative therapies and underscores the importance of India as a key player in global clinical research.
CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
Defecation
Normal defecation begins with movement in the left colon, moving stool toward the anus. When stool reaches the rectum, the distention causes relaxation of the internal sphincter and an awareness of the need to defecate. At the time of defecation, the external sphincter relaxes, and abdominal muscles contract, increasing intrarectal pressure and forcing the stool out
The Valsalva maneuver exerts pressure to expel faeces through a voluntary contraction of the abdominal muscles while maintaining forced expiration against a closed airway. Patients with cardiovascular disease, glaucoma, increased intracranial pressure, or a new surgical wound are at greater risk for cardiac dysrhythmias and elevated blood pressure with the Valsalva maneuver and need to avoid straining to pass the stool.
Normal defecation is painless, resulting in passage of soft, formed stool
CONSTIPATION
Constipation is a symptom, not a disease. Improper diet, reduced fluid intake, lack of exercise, and certain medications can cause constipation. For example, patients receiving opiates for pain after surgery often require a stool softener or laxative to prevent constipation. The signs of constipation include infrequent bowel movements (less than every 3 days), difficulty passing stools, excessive straining, inability to defecate at will, and hard feaces
IMPACTION
Fecal impaction results from unrelieved constipation. It is a collection of hardened feces wedged in the rectum that a person cannot expel. In cases of severe impaction the mass extends up into the sigmoid colon.
DIARRHEA
Diarrhea is an increase in the number of stools and the passage of liquid, unformed feces. It is associated with disorders affecting digestion, absorption, and secretion in the GI tract. Intestinal contents pass through the small and large intestine too quickly to allow for the usual absorption of fluid and nutrients. Irritation within the colon results in increased mucus secretion. As a result, feces become watery, and the patient is unable to control the urge to defecate. Normally an anal bag is safe and effective in long-term treatment of patients with fecal incontinence at home, in hospice, or in the hospital. Fecal incontinence is expensive and a potentially dangerous condition in terms of contamination and risk of skin ulceration
HEMORRHOIDS
Hemorrhoids are dilated, engorged veins in the lining of the rectum. They are either external or internal.
FLATULENCE
As gas accumulates in the lumen of the intestines, the bowel wall stretches and distends (flatulence). It is a common cause of abdominal fullness, pain, and cramping. Normally intestinal gas escapes through the mouth (belching) or the anus (passing of flatus)
FECAL INCONTINENCE
Fecal incontinence is the inability to control passage of feces and gas from the anus. Incontinence harms a patient’s body image
PREPARATION AND GIVING OF LAXATIVESACCORDING TO POTTER AND PERRY,
An enema is the instillation of a solution into the rectum and sig
2. Interventional Research
• Studies in which investigator assigns the exposure
• Often used to determine the effectiveness of an intervention or
effectiveness of a health service delivery.
• Can also be used to establish the safety, cost-effectiveness and
acceptability of an intervention.
Prabesh Ghimire, MPH 2
4. Before we begin…
Experimental designs involve:
• Groups: Intervention and Control
• One-group design: only intervention group, no controls
• Two-group design: both intervention group and control group
• Four-groups design
• Tests/Assessments: Pre-test and Post-test
• Post-test only design
• Pre-test post-test design
• Randomization: Randomized and Non-randomized
• Equivalent design: groups are randomly allocated
• Non-equivalent design: groups are not allocated randomly
Prabesh Ghimire, MPH 4
5. Before we begin…
Baseline/ Pre-test Intervention Endline/Post-test
Intervention Group
(I1)
X Intervention Group
(I2)
Control Group (C1) Control Group (C2)
Randomization
Prabesh Ghimire, MPH 5
6. Before we begin…
Understanding the notations used in this presentation:
• I1 – Pre-test in the intervention group
• I2 – Post-test in the intervention group
• C1 – Pre-test in the control group
• C2 – Post-test in the control group
• X – Intervention
Prabesh Ghimire, MPH 6
7. Pre-Experimental Study Design
• In a pre-experiment, either a single group or multiple groups are
observed subsequent to some agent or treatment presumed to
cause change.
• Pre-experimental designs either fail to include a pretest, a
control or comparison group, or both
• In addition, no randomization procedures are used to control for
extraneous variables.
• When true experiments and quasi-experiments are not possible,
researchers may turn to a pre-experimental design
Prabesh Ghimire, MPH 7
8. Pre-Experimental Study Design
• Useful in cases where a researcher cannot control or predict
whether, when, or how the stimulus is administered, as in the case of
natural disasters (chemical poisoning, earthquake)
• They are considered “pre-,” indicating they are preparatory or
prerequisite to true experimental designs.
• Often, researchers want to see if their interventions will have an effect on a
small group of people before they seek funding and dedicate time to conduct
a true experiment.
• Usually conducted as a first step towards establishing the evidence
for or against an intervention.
Prabesh Ghimire, MPH 8
9. Types of Pre-Experimental Design
1. One-Shot Case Study (One group post-test design)
2. Static Group Comparison (Post-test only non-equivalent
group design)
3. One-group pre-test/ post-test design
Prabesh Ghimire, MPH 9
10. Types of Pre-Experimental Design
1. One-Shot Case Study (Ex post facto design)
• One group only post-test design
• A single group of people is measured on some dependent variable after
intervention has taken place.
• A group is administered a covid-19 vaccine and then followed up for
certain period to check if they present a COVID infection.
• Useful in cases where the administration of the stimulus is quite costly or
otherwise not possible (example disaster)
• In this instance, no pretest is administered, nor is a control group present.
X O2
(Intervention) (Post-Test)
Prabesh Ghimire, MPH 10
11. Types of Pre-Experimental Design
1. One-Shot Case Study
• In the study of the impact of earthquake (natural intervention),
• Researcher using this design would test the impact of earthquake only among
a community that was hit by earthquake
• Would not seek a comparison group from a community that did not
experience the earthquake.
I1 X I2 (earthquake hit)
(No pre-test) (Earthquake) (Post-Test)
• Researchers using a one-shot case study design must be extremely
cautious when making claims about the effect of the stimulus,
Prabesh Ghimire, MPH 11
12. Types of Pre-Experimental Design
2. Static Group Comparison (Post-test only non-equivalent group design)
• In the study of the impact of earthquake, researcher using this
design
• Identifies an experimental group from a community that experienced the
earthquake; and
• Control group from a similar community that had not been hit by the
earthquake
I1 X I2 (hit by earthquake)
C1 C2 (not hit by earthquake)
(No pre-test) (Earthquake) (Post-Test)
Prabesh Ghimire, MPH 12
13. Types of Pre-Experimental Design
3. Static Group Comparison
• Has the advantage of including a comparison group that did not
experience the stimulus (earthquake)
• It is difficult to be sure that the groups are truly comparable
because the experimental and control groups were determined
by factors other than random assignment.
• The design would only allow for posttests
Prabesh Ghimire, MPH 13
14. Types of Pre-Experimental Design
3. One-group pre-test/ post-test design
• Research designs in which
• a single group of research participants or subjects is pretested,
• given some treatment/ intervention,
• then post-tested.
• In this instance, pre- and posttests are both taken, but there is no
control group to compare the experimental group to.
I1 (Pre-test) X I2 (vaccinated)- Post-test
C1 (No pre-test) C2 (no control/ no post-test)
(COVID Vaccine)
Prabesh Ghimire, MPH 14
15. Types of Pre-Experimental Design
3. One-group pre-test/ post-test design
• If the pretest and posttest scores differ significantly, then the
difference may be attributed to the intervention.
• But because the research design is not strictly experimental and
there is no control group, this inference is uncertain,
• Useful when
• a researcher cannot identify a sample that is large enough to split into
control and experimental groups
• Researcher do not have access to a control group
Prabesh Ghimire, MPH 15
16. Pre-Experimental Study Design
Strengths
• Pre-experiments can be a cost-effective way to discern whether
a potential explanation is worthy of further investigation.
• Useful in cases where a researcher cannot control or predict
whether, when, or how the stimulus is administered, as in the
case of natural disasters
Limitations
• Subject to numerous threats to their validity.
Prabesh Ghimire, MPH 16
18. Quasi-Experimental Design
• Experimental studies that lack random assignment to
experimental and control groups.
• Useful in the cases where experimental and control groups
already exist. For example:
• a researcher might conduct research at two different agency sites, one
of which receives the intervention and the other does not.
• The researcher does not need to assigned participants to treatment or
comparison groups because the groupings already existed prior to the
study.
Prabesh Ghimire, MPH 18
19. Quasi-Experimental Design
• Quasi-experiments are most likely to be conducted in field settings in
which random assignment is difficult or impossible.
• While this method is more convenient for real-world research, researchers
cannot be sure that the groups are comparable.
• Often used to evaluate the effectiveness of a treatment (psychotherapy) or
an educational intervention.
• Useful tool in situations where true experiments cannot be used for ethical
or practical reasons.
• Example: it would be unethical to randomly provide some people with covid vaccine
but purposely prevent others from receiving it solely for the purpose of research.
Prabesh Ghimire, MPH 19
20. Types of Quasi-Experimental Design
• Pre-test post-test non-equivalent control group design
• Interrupted time series design
• Regression discontinuity analysis
Prabesh Ghimire, MPH 20
21. Types of Quasi-Experimental Design
• Pre-Test Post-test Non-equivalent Control Group Design
Group Baseline/ Pre-
test
Intervention Endline/Post-
test
Intervention
Group
Pre-Test X Post-Test
Control Group Pre-Test Post-Test
No
Randomization
Prabesh Ghimire, MPH 21
23. Time Series Design
• Type of quasi experimental design
• Time series: set of measurements taken at intervals over a
period of time.
• In this design, a series of periodic measurements is taken from
one group of study units, followed by treatment, then another
series of measurements.
• Time Series Design collects data on the same variable at
regular intervals (weeks, months, years, etc.) in the form of
aggregate measures of a population.
• Example: Unemployment rates, accident rates, fatality rate
Prabesh Ghimire, MPH 23
24. Time Series Design
March (T-3) April (T-2) May (T-1) Intervention July (T+1) August (T+2) September
(T+3)
Fatality rate Fatality rate Fatality rate Crackdown Fatality rate Fatality rate Fatality rate
Province March (T-
3)
April (T-2) May (T-1) Interventi
on
July (T+1) August
(T+2)
Septembe
r (T+3)
Lumbini Fatality
rate
Fatality
rate
Fatality
rate
Crackdow
n
Fatality
rate
Fatality
rate
Fatality
rate
Bagmati Fatality
rate
Fatality
rate
Fatality
rate
Fatality
rate
Fatality
rate
Fatality
rate
One group - Interrupted Time Series Design
Interrupted Time Series Design with comparison group
Prabesh Ghimire, MPH 24
25. Time Series Design
Time Series Design are useful for:
• Establishing a baseline measure
• Describing changes over time
• Keeping track of trends
• Forecasting future trends
Prabesh Ghimire, MPH 25
26. • Time series data are nearly always presented in the form of a
chart or graph.
• The horizontal (or x) axis is divided into time intervals
• The vertical (y) axis shows the values of the dependent variable
as they fluctuate over time.
Time Series Design
Prabesh Ghimire, MPH 26
28. True Experimental Design
• Design used to refer to any randomized experiments
• Carried out with or without a pretest/ baseline on at least 2
randomly assigned subjects.
• For the true experimental design, following criteria should be
met:
• Control group must be present
• A variable that can be manipulated by the researcher (e.g. dose)
• Randomization
Prabesh Ghimire, MPH 28
29. Techniques of random selection and
participant assignment
• Referring to a random number table
• Computer generated random number
• Coin tossing
• Shuffling cards or envelopes
• Throwing dice
• Sequentially numbered drug containers of identical appearance
• Sequentially numbered, opaque, sealed envelopes
Prabesh Ghimire, MPH 29
30. Techniques of random selection and
participant assignment
High risk of bias if
• Sequence generated by odd or even date of birth, day of visit,
etc.
• Allocation by judgment of clinician, participant
• Allocation based on results of laboratory test
• Case record number
• Unsealed or non-opaque envelopes
Prabesh Ghimire, MPH 30
31. Types of True Experimental Design
1. Post-test only control group design
2. Pre-test Post-test control group design
3. Solomon four group design
Prabesh Ghimire, MPH 31
32. Types of True Experimental Design
1. Post-Test Only Control Group Design
• Study participants are randomly selected and assigned to the 2
groups (control and experimental), and only the experimental group
is treated/intervened.
• Neither group is assessed/ pre-tested before intervention
• After close observation, both groups are post-tested, and a
conclusion is drawn from the difference between these group.
I1 X I2
C1 C2
(No pre-test) (Dexamethasone) (Post-test)
Randomization
Prabesh Ghimire, MPH 32
33. Types of True Experimental Design
2. Pre-Test Post-Test Control Group Design
• Subjects are randomly assigned to the 2 groups
• Both are pre-tested
• Only the intervention group is treated.
• After close observation, both groups are post-tested to measure
the degree of change in each group.
I1 X I2
C1 C2
(Pre-test) (Dexamethasone) (Post-test)
Randomization
Prabesh Ghimire, MPH 33
34. Types of True Experimental Design
3. Solomon Four Group Design
• In this design, the sample is divided into two treatment groups
and two control groups.
• One treatment group and one control group receive the pretest,
and the other two groups do not.
• This design represents a combination of posttest-only and
pretest-posttest control group design, and is intended to test for
the potential biasing effect of pretest measurement on posttest
measures that tends to occur in pretest-posttest designs but not
in posttest only designs.
Prabesh Ghimire, MPH 34
35. Types of True Experimental Design
3. Solomon Four Group Design
I1 (No pre-test) X I2 (Post-test)
C1 (No pre-test) C2 (Post-test)
I1 (Pre-test) X I2 (Post-test)
C1 Pre-test) C2 (Post-test)
Prabesh Ghimire, MPH 35
36. Assignment
Review each of the following study designs:
• One-shot case study (one-group post-test only design)
• Static group comparison (post-test only, non-equivalent group
design)
• One group pre-test post-test design
• Non-equivalent group, pre-test post-test design
• Post-test only, control group design (equivalent group)
• Pre-test Post-test control group design (non-equivalent group)
• Pre-test post-test control group design
Prabesh Ghimire, MPH 36
38. Clinical Trial
• Research design that studies new tests/therapies and
treatments and evaluates their effects on human health
outcomes.
• The purpose of the clinical trial is assessment of efficacy, safety,
or risk benefit ratio.
• Clinical trials are carefully designed, reviewed and completed,
and need to be approved before they can start.
• Interventions may be prophylactic, therapeutic or diagnostic:
• Novel vaccines, drugs, dietary choices, dietary supplements, medical
devices
Prabesh Ghimire, MPH 38
39. Research Question in Clinical Trial
• Types of questions
• Assessing efficacy of an intervention
• Assessing the effectiveness of an intervention
Prabesh Ghimire, MPH 39
40. Phases in Clinical Trial
• There are 4 phases of biomedical clinical trials:
• Phase I studies usually test new drugs for the first time in a small
group of people to evaluate a safe dosage range and identify side effects.
• Phase II studies test treatments that have been found to be safe in phase I
but now need a larger group of human subjects to monitor for any
adverse effects.
• Phase III studies are conducted on larger populations and in different
regions and countries, and are often the step right before a new
treatment is approved.
• Phase IV studies take place after country approval and there is a need for
further testing in a wide population over a longer timeframe.
Click here for further reading
Prabesh Ghimire, MPH 40
42. Types of Clinical Trial
• Uncontrolled Trials
• Controlled Trials
• Non-randomized controlled trial
• Randomized controlled trial/ Randomized clinical trial
Control arm options in controlled trials
• Placebo concurrent control
• “No treatment” concurrent control
• Active treatment concurrent control
• Dose-comparison concurrent control
Prabesh Ghimire, MPH 42
43. Uncontrolled Trial
• This design incorporates no control arm.
• This design is usually utilized to determine pharmacokinetic
properties of a new drug (Phase 1 trials).
• Uncontrolled trials are known to produce greater mean effect
estimates than a controlled trial, thereby inflating the
expectations from the intervention.
• There is a threat of inherent bias and results are considered
less valid than RCT.
Prabesh Ghimire, MPH 43
44. Uncontrolled Trial
Nair B. (2019). Clinical Trial Designs. Indian dermatology online journal, 10(2), 193–201.
https://doi.org/10.4103/idoj.IDOJ_475_18
Prabesh Ghimire, MPH 44
45. Randomized Controlled Trial
• A part of clinical trial
• In RCTs the patients are randomly assigned to the different
study groups.
• This is intended to ensure that all potential confounding factors
are divided equally among the groups that will later be
compared
Prabesh Ghimire, MPH 45
48. Strengths and Limitations
Strengths
• Often provides the strongest evidence in support of cause-effect
relationships
• Basis for clinical and public health policy
• Excellent internal validity; removes validity threats
• Provides precise measures of efficacy and acute toxicity of new
therapies under ideal conditions.
• Because of randomization, measurement of effect size is less
prone to bias.
Prabesh Ghimire, MPH 48
49. Strengths and Limitations
Limitations
• Limited external validity
• Patients with co-morbidity are under-represented in RCTs.
• Have limited ability to detect rare and chronic toxicities, especially
those that occur in patients after the completion of the trial.
• Chances of experimental mortality (attrition) cannot be ruled out.
• Might be costly
• Some research problems cannot be studied using an experiment
because of ethical or technical reasons.
Prabesh Ghimire, MPH 49
51. Parallel Group Trial Design
• Most commonly used study design/ classical RCT
• Study participants are randomized to one of two groups
• The two group, usually comprise an interventional group and a
comparator group, which are followed forward in time.
• The comparator group may receive placebo or standard of care
• After randomization each participant will stay in their assigned
treatment arm throughout the study.
Prabesh Ghimire, MPH 51
52. Parallel Group Trial Design
Group
A
Group
B
Tinmouth A, Hebert P. Interventional trials: an overview of design alternatives. Transfusion. 2007
Apr;47(4):565-7. doi: 10.1111/j.1537-2995.2007.01202.x. PMID: 17381612.
Prabesh Ghimire, MPH 52
53. Parallel Groups
• Multiple concurrent experimental arms
• Different treatments
• Different doses
• Control arms
• Placebo
• Active control (known effective treatment)
Prabesh Ghimire, MPH 53
54. Parallel Group Design
Strengths
• Can be applied to many diseases and allows running
experiments simultaneously in a number of groups, and groups
can be in separate locations.
• Simplest design to plan, implement, analyze, and interpret
Limitations
• People dislike the possibility of receiving placebo, so it could be
a deterrent for them to sign up to participate.
Prabesh Ghimire, MPH 54
55. Cross-Over Design
• This approach randomly assigns participants to one group, who
then “crossover" to another treatment arm during the course of
the trial.
• Uses individual as their own controls
• This means that even if they are initially put into a placebo
group, they will also eventually receive the study drug or
standard of care during the trial.
Prabesh Ghimire, MPH 55
56. Cross-Over Design
Group
A
Group
B
Group
B
Group
A
Tinmouth A, Hebert P. Interventional trials: an overview of design alternatives. Transfusion. 2007
Apr;47(4):565-7. doi: 10.1111/j.1537-2995.2007.01202.x. PMID: 17381612.
Prabesh Ghimire, MPH 56
57. Cross-Over Design
• Patients are assigned to receive two treatments in a random
order.
• Each treatment is given a defined period of time with a washout
period between the two treatments
• The washout period between the two intervention phases is
included to reduce carryover effects from the previous
treatments
• helps researchers determine whether the outcome of the study is due
to the effects of the study drug.
Prabesh Ghimire, MPH 57
58. Cross-Over Design
• In this design, some participants start with drug A and then
switch to drug B (AB sequence) in one trial arm,
• While participants in other trial arm start with drug B and then
switch to drug A (BA sequence).
Prabesh Ghimire, MPH 58
59. Cross-Over Design
Strengths
• Require fewer patients than a parallel study since each patient acts as his or her
own control.
• Minimizes between subject variability
• Ethical- opportunity to receive both treatments
• Best suited to patients with chronic conditions with stable symptoms.
Limitations
• Take longer to complete since patients will receive multiple treatments during the
trial.
• Many patients may withdraw due to longer study period
• Carryover effects from treatments may impact results
• Period effects are likely (progression of disease, dropouts)
Prabesh Ghimire, MPH 59
60. Other Designs
• Factorial Design
• Evaluates different interventions alone and in combination.
• In 2*2 factorial design four groups are compared
• Therapy A
• Therapy B
• Therapy A+B in combination
• No therapy
Prabesh Ghimire, MPH 60
61. Other Designs
• Cluster Design (Cluster RCT)
• Groups or clusters are randomly assigned, not individuals E.g. classes,
hospital wards, quarantine centers, platoons….
• Useful in educational research.
Ward
A
Ward
B
Prabesh Ghimire, MPH 61
62. For further reading
• Tinmouth A, Hebert P. Interventional trials: an overview of design
alternatives. Transfusion. 2007 Apr;47(4):565-7. doi: 10.1111/j.1537-
2995.2007.01202.x. PMID: 17381612.
• Kabisch, M., Ruckes, C., Seibert-Grafe, M., & Blettner, M. (2011).
Randomized controlled trials: part 17 of a series on evaluation of scientific
publications. Deutsches Arzteblatt international, 108(39), 663–668.
https://doi.org/10.3238/arztebl.2011.0663
• Nair B. (2019). Clinical Trial Designs. Indian dermatology online
journal, 10(2), 193–201. https://doi.org/10.4103/idoj.IDOJ_475_18
Prabesh Ghimire, MPH 62
63. Community Trial
• Community trials, also called community intervention studies,
are (mostly preventive) experimental studies with whole
communities (such as cities or states) as experimental units
• Interventions are assigned to all members in each of a number
of communities.
• Carried out “on the ground”.
Prabesh Ghimire, MPH 63
67. Rationale for community trial
• Environmental change may be easier that voluntary behaviour
(cigarette tax vs. stop smoking)
• Some interventions are not selective (e.g. water fluoridation,
IRS)
• Individual randomization may not be feasible because all
members of group are treated same.
• Individual randomization, although feasible, may result in
substantial contamination.
Prabesh Ghimire, MPH 67
68. Community Trial Designs
• Single community
• Before-after: O1 X O2
• Single (interrupted) time series: O1 O2 O3 X O4 O5 O6
• One intervention and one control community
O x O
O O
• One intervention and multiple control communities
• Multiple intervention and control communities
Prabesh Ghimire, MPH 68
70. Concept of Blinding
• Concealment of group allocation from one or more individuals
involved in a research study
• Most commonly a RCT
• Also called masking
• Blinding is used in combination with randomization to limit the
occurrence of conscious and unconscious bias
• in the conduct of clinical trials (performance bias) and
• interpretation of outcomes (ascertainment bias).
Prabesh Ghimire, MPH 70
71. Concept of Blinding
• This is important because bias can affect recruitment and
allocation, care, attitudes, assessments, etc.
• Minimizes the likelihood of differential treatment or assessments
of outcomes
• Used to ensure the objectivity of trial results
Prabesh Ghimire, MPH 71
72. Whom to Blind?
1. Study Participants
2. Data Collectors and Outcome Assessors
3. Clinicians administering the treatment
4. Data Analyst
Prabesh Ghimire, MPH 72
73. Whom to Blind?
1. Study Participants
• If participants are not blinded, knowledge of group assignment
may affect their behaviour in the trial and their responses to
subjective outcome measures.
• Blinded patients may report symptoms differently from
unblinded patients
• For example, a participant who is aware that he is not receiving
active treatment may be
• less likely to comply with the trial protocol,
• more likely to seek additional treatment outside of the trial and
• more likely to leave the trial without providing outcome data.
Prabesh Ghimire, MPH 73
74. Whom to Blind?
2. Data collectors/ Outcome assessors
• Crucial to ensure unbiased ascertainment of outcomes.
• Helps to reduce detection bias.
• Outcome assessors (study nurses or investigators) who are
aware of the actual treatment may unconsciously or
intentionally alter their assessment.
• Particularly, in case of soft endpoints, e.g. pain blinding of
outcome assessors is important.
• For hard comparators like mortality detection bias is irrelevant
Prabesh Ghimire, MPH 74
75. Whom to Blind?
3. Clinicians administering the treatment
• Blinded clinicians are much less likely to transfer their attitudes
to participants or to provide differential treatment to the active
and placebo groups than are unblinded clinicians
Prabesh Ghimire, MPH 75
76. Whom to Blind?
4. Data analyst
• Bias may also be introduced during the statistical analysis of the
trial through the selective use and reporting of statistical tests.
• This may be a subconscious process spurred by investigators
eager to see a positive result.
• The best method to avoid this potential bias is blinding of the
data analyst until the entire analysis has been completed.
Prabesh Ghimire, MPH 76
77. Biases due to lack of blinding
• Performance bias
• Detection/ bias
• Participant’s expectation bias
• Data analysts
• Observer bias
Prabesh Ghimire, MPH 77
78. Types of Blinding
• Unblinded
• All parties are aware of the treatment the participant receives
• Single blind
• Only the participant is unaware of the treatment they receive
• Double blind
• The participant and the clinicians / data collectors are unaware of the
treatment the participant receives
• Triple blind
• Participant, clinicians and data collectors / outcome assessors / data analysts
are all unaware of the treatment the participant receives
Prabesh Ghimire, MPH 78
79. How to blind?
• Drug trial: matching the placebo in color, taste and dosing
schedule.
• Not informing patients of what group they are in
• Using independent outcome assessors
• Not disclosing allocation to data analysts:
• Example using variable names as GrpA, GrpB instead of EXP & CTRL
groups
Prabesh Ghimire, MPH 79
80. For further reading
• Karanicolas, P. J., Farrokhyar, F., & Bhandari, M. (2010). Practical tips for
surgical research: blinding: who, what, when, why, how?. Canadian journal
of surgery. Journal canadien de chirurgie, 53(5), 345–348.
• Boutron, I., Estellat, C., Guittet, L., Dechartres, A., Sackett, D. L.,
Hróbjartsson, A., & Ravaud, P. (2006). Methods of blinding in reports of
randomized controlled trials assessing pharmacologic treatments: a
systematic review. PLoS medicine, 3(10), e425.
https://doi.org/10.1371/journal.pmed.0030425
Prabesh Ghimire, MPH 80