This document discusses experimental and quasi-experimental designs used in research. It begins by listing learning objectives related to recognizing when experiments are suitable, describing key aspects of classical experiments, and understanding quasi-experiments. The classical experiment is then explained in more detail, focusing on independent and dependent variables, pretesting and posttesting, experimental and control groups, and threats to internal validity. The document also discusses variations of experimental designs, quasi-experimental designs when randomization is not possible, and threats to validity and generalizability.
This document discusses experimental and quasi-experimental designs. It outlines the key components of classical experimental designs, including independent and dependent variables, experimental and control groups, pretesting and posttesting. It also discusses threats to internal and external validity and variations like quasi-experimental designs that use nonequivalent groups or time series when randomization is not possible. Quasi-experiments aim to make groups as comparable as possible through matching or using natural cohorts.
Experimental and quasi-experimental designs involve manipulating an independent variable and observing its effects on a dependent variable. Key aspects include establishing experimental and control groups, pretesting and posttesting to measure the dependent variable both before and after exposure to the independent variable, and using random assignment or matching to make the groups as equivalent as possible. Threats to internal and external validity must be considered, and variations can be created by manipulating the number of groups, stimuli, measurements, and subject selection/assignment procedures.
Experimental design involves purposefully introducing changes or treatments to observe their effects. The document discusses key aspects of experimental design, including:
1. Selecting subjects and assigning them to treatment or control groups to measure the effect of changes.
2. Considering factors like the type and amount of information desired, questions the design will and won't answer, and costs when selecting a design.
3. Key terminology like treatment, control, variables, randomness, and validity that are important to experimental design.
Experimental studies allow researchers to determine cause-and-effect relationships. They involve manipulating an independent variable and measuring its effect on a dependent variable. Well-designed experiments include controls to minimize the influence of other variables. Clinical trials are a type of experimental study used to test new medical treatments in humans. They proceed through four phases to evaluate safety, efficacy, and effectiveness. Randomized controlled trials are considered the gold standard as they randomly assign participants to experimental and control groups to determine causal effects.
Internal and External threat to ValidityZehra Khushal
This document discusses research design methods in survey and experimental research. It describes key aspects of the survey method, including that it is a descriptive design that collects self-reported data through questions administered via interviews or questionnaires. Steps in survey design are outlined, including defining objectives, sampling, distribution of questionnaires, and follow-ups. Experimental design is described as the only method that can establish cause-and-effect through manipulation of independent variables and measurement of dependent variables. Types of experimental designs and threats to internal and external validity are summarized.
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.
The document discusses the experimental method of research. It describes key features of experiments including manipulating an independent variable to observe its effect on a dependent variable. This allows researchers to establish cause-and-effect relationships. The document also discusses variables, demand characteristics, types of experiments (laboratory, field, natural), experimental designs, hypotheses, significance, sampling, and other research methods like surveys, interviews, and observation.
The document discusses experimental and quasi-experimental research designs. It defines experimental design as procedures where the researcher determines whether an activity makes a difference in results for participants by giving one group an intervention and withholding it from another group. The document outlines characteristics of experimental designs such as random assignment, manipulation of treatment conditions, and outcome measures for comparing groups. It also discusses advantages and disadvantages of experimental and quasi-experimental designs.
This document discusses experimental and quasi-experimental designs. It outlines the key components of classical experimental designs, including independent and dependent variables, experimental and control groups, pretesting and posttesting. It also discusses threats to internal and external validity and variations like quasi-experimental designs that use nonequivalent groups or time series when randomization is not possible. Quasi-experiments aim to make groups as comparable as possible through matching or using natural cohorts.
Experimental and quasi-experimental designs involve manipulating an independent variable and observing its effects on a dependent variable. Key aspects include establishing experimental and control groups, pretesting and posttesting to measure the dependent variable both before and after exposure to the independent variable, and using random assignment or matching to make the groups as equivalent as possible. Threats to internal and external validity must be considered, and variations can be created by manipulating the number of groups, stimuli, measurements, and subject selection/assignment procedures.
Experimental design involves purposefully introducing changes or treatments to observe their effects. The document discusses key aspects of experimental design, including:
1. Selecting subjects and assigning them to treatment or control groups to measure the effect of changes.
2. Considering factors like the type and amount of information desired, questions the design will and won't answer, and costs when selecting a design.
3. Key terminology like treatment, control, variables, randomness, and validity that are important to experimental design.
Experimental studies allow researchers to determine cause-and-effect relationships. They involve manipulating an independent variable and measuring its effect on a dependent variable. Well-designed experiments include controls to minimize the influence of other variables. Clinical trials are a type of experimental study used to test new medical treatments in humans. They proceed through four phases to evaluate safety, efficacy, and effectiveness. Randomized controlled trials are considered the gold standard as they randomly assign participants to experimental and control groups to determine causal effects.
Internal and External threat to ValidityZehra Khushal
This document discusses research design methods in survey and experimental research. It describes key aspects of the survey method, including that it is a descriptive design that collects self-reported data through questions administered via interviews or questionnaires. Steps in survey design are outlined, including defining objectives, sampling, distribution of questionnaires, and follow-ups. Experimental design is described as the only method that can establish cause-and-effect through manipulation of independent variables and measurement of dependent variables. Types of experimental designs and threats to internal and external validity are summarized.
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.
The document discusses the experimental method of research. It describes key features of experiments including manipulating an independent variable to observe its effect on a dependent variable. This allows researchers to establish cause-and-effect relationships. The document also discusses variables, demand characteristics, types of experiments (laboratory, field, natural), experimental designs, hypotheses, significance, sampling, and other research methods like surveys, interviews, and observation.
The document discusses experimental and quasi-experimental research designs. It defines experimental design as procedures where the researcher determines whether an activity makes a difference in results for participants by giving one group an intervention and withholding it from another group. The document outlines characteristics of experimental designs such as random assignment, manipulation of treatment conditions, and outcome measures for comparing groups. It also discusses advantages and disadvantages of experimental and quasi-experimental designs.
This document discusses key elements in research design including causation, units of analysis, and time. It addresses causation in social science research and the criteria for determining causality. The four types of validity threats - statistical conclusion, internal, external, and construct validity - are summarized. Different units of analysis like individuals, groups, organizations, and social artifacts are also outlined. Finally, the document contrasts cross-sectional and longitudinal research, including trends, cohorts, panels, and how retrospective studies can approximate longitudinal data.
This document discusses single factor experimental research design. It describes the significant properties of randomization and manipulation of a single independent variable with at least two levels. It outlines types of single factor designs including between-subject and within-subject designs. It discusses threats to internal validity such as maturation and instrumentation. The document also notes ethical issues and advantages/limitations of this research design. Finally, it summarizes two examples of single factor experimental studies conducted in Pakistan.
This document discusses and compares various study designs used in medical research, including observational studies like case reports, case series, case-control studies, and cohort studies as well as experimental studies like randomized controlled trials. It provides descriptions of each study design along with their pros and cons. For example, it notes that case reports are useful for raising hypotheses but very rare to use to make statements of causation, while randomized controlled trials allow for control of therapy but have ethical and cost issues.
This presentation by John E. Kwoka, Neal F. Finnegan Distinguished Professor of Economics, Northeastern University, was made during the discussion “Ex-post Assessment of Merger Remedies” held at the 22nd meeting of the OECD Global Forum on Competition on 8 December 2023. More papers and presentations on the topic can be found out at oe.cd/eamr.
This presentation was uploaded with the author’s consent.
This document discusses key concepts in operationalizing and measuring variables in social science research. It covers how concepts are abstract mental representations that must be defined and measured concretely through operationalization. Operationalization involves developing observable indicators and dimensions of concepts. Measurement then assigns numerical or categorical values to those indicators. The document emphasizes creating exhaustive and mutually exclusive measurement categories and discusses different levels of measurement. It also outlines criteria for ensuring quality in measurement, including reliability, validity, and using composite measures and indexes.
Chapter 2
Study Designs
Learning Objectives
• List and define the components of a good
study design
• Compare and contrast observational and
experimental study designs
• Summarize the advantages and disadvantages
of alternative study designs
Learning Objectives
• Describe the key features of a randomized
controlled trial
• Identify the study designs used in public health
and medical studies
Study Designs
• Observational Studies
– Case-series study
– Cross-sectional (prevalence) survey
– Case-control study
– Cohort study
• Experimental Studies
– Randomized Controlled (Clinical) Trial
Inferences
• Observational studies – inferences limited to descriptions
and associations; with carefully designed analysis can
make stronger inferences (statistical adjustment)
• Experimental studies – cause and effect
In ALL studies – need careful definition of disease
(outcome) and exposure (risk factor)
Which Design is Best
• Depends on the study question
• What is current knowledge on topic
• How common is disease (and risk factors)
• How long would study take, what are costs
• Ethical issues
Case Report/Case Series
• Observational study
• Case report: Detailed report of specific
features of case
• Case series: Systematic review of common
features of a small number of cases
• Advantage: Cost-efficient
• Disadvantages: No comparison group, no
specific research question
Case-Series
• Simplest design – description of interesting
observations in a small number of individuals
• Usually case-series do not involve control patients
(i.e., patients free of disease)
• Usually lead to generation of hypotheses for more
formal testing
• Criticisms: not planned – no research hypotheses
Case-Series
• Gottleib (1981) studied 5 young homosexual
men with rare form of pneumonia and other
unusual infections
• Initial report was followed by more series (26
cases in NY and CA; “cluster” in southern CA;
34 cases among Haitians, etc.)
• Condition termed AIDS in 1982
Cross-Sectional Survey
• Observational study conducted at a point in
time
• Advantages: Cost-efficient, easy to implement,
ethical
• Disadvantages: No temporal information, non-
response bias
Cross-Sectional Survey
• Is there an association between diabetes and
cardiovascular disease (CVD)?
Patients
with
Diabetes
Patients without
Diabetes
Patients with
CVD
Prospective Cohort Study
• Observational study involving a group (cohort)
of individuals who meet inclusion criteria
followed prospectively in time for risk factor
and outcome information
• Advantages: Can assess temporal relationships
• Disadvantages: Need large numbers for rare
outcomes, confounding
Cohort Study
• Is there an association between hypertension and
cardiovascular disease?
CVD
Hypertension
No CVD
Cohort
CVD
No Hypertension
No CVD
Study Start Time
Cohort Studies
• Identify a group of individuals that meet
inclusion crit ...
Sardar CK DPT MSPT EBP Lecture 3 Part 1.pptxChangezKhan33
This document discusses different types of evidence that can be used to evaluate clinical interventions. It begins by describing clinical observation and the limitations of relying only on observation due to potential confounding variables. It then discusses different types of clinical research designs including case reports, case series, controlled trials, randomized trials, and systematic reviews. Randomized trials and systematic reviews are considered the best evidence as they aim to control for bias. The document concludes by noting while these designs provide quantification of effects, they may neglect patients' experiences, requiring different research approaches.
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.
Random control trial RCT community medicine .pptxAkshayRaj781072
The document discusses randomized controlled trials (RCTs), which are considered the gold standard for evaluating the effectiveness of medical interventions. It provides definitions of key RCT concepts like randomization, blinding, and intention-to-treat analysis. RCTs follow a strict protocol and involve randomly assigning participants to experimental and control groups, intervening, following up, and assessing outcomes while limiting bias. Well-conducted RCTs can establish whether medical treatments, devices, or services are efficacious compared to alternatives.
Adlt673 session 5_quantitative_validity_practicatility - class 5tjcarter
This document discusses research design and methodology. It begins by introducing different types of research designs, including experimental and non-experimental. It then covers key aspects of research such as developing hypotheses, defining variables, and establishing validity. Specific challenges of classroom-based research are also addressed. The document provides guidance on selecting an appropriate research design based on the study context and limitations. It emphasizes that every design has tradeoffs, and the best approach depends on the research question and constraints.
Factors that influence internal and external validity of.pptxAnanthiD6
Internal validity refers to whether the observed effects in an experiment can be attributed to the manipulation of the independent variable rather than other factors. Key factors influencing internal validity include controlling extraneous variables, randomization, experimental design, pre-testing and post-testing, placebo effects, and blinding. External validity concerns the generalizability of findings to other populations, settings, and times. Factors impacting external validity include population characteristics, sampling method, setting and context, timeframe, ecological validity, and cross-cultural considerations. Balancing internal and external validity is often a trade-off, so researchers must design experiments to achieve the right balance based on their research goals.
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
This document provides an overview of quantitative research methods. It defines quantitative research as a formal, objective, and systematic process used to generate information. The main types of quantitative research described are descriptive research, correlational research, quasi-experimental research, and experimental research. Experimental research aims to determine cause-and-effect relationships through controlled manipulation of variables and random assignment to groups. The steps of the quantitative research process include defining the problem, reviewing literature, identifying variables, collecting and analyzing data, and reporting results.
Here are some key points to consider in your discussion:
- Given the complexity of the project operating in a weak health system with resistant communities, a complexity-aware approach would be well-suited to understand the relationships between actors and pathways of change over time.
- Mixed methods would allow triangulation between qualitative data to understand relationships and pathways of change with quantitative data to measure outcomes. Starting with qualitative data collection in year 1 could help develop appropriate indicators for year 2.
- Quasi-experimental methods like a comparison pre-post design could measure outcomes but selection bias may be difficult to control for given the scale and nature of the intervention. Qualitative data would help understand any differences observed.
- Using a participatory
This document discusses the different types of validity in psychological testing: face validity, content validity, criterion validity (including predictive and concurrent validity), and discriminant validity. It provides examples for each type of validity. Criterion validity refers to how a test correlates with other measures of the same construct. Discriminant validity shows a test does not correlate with measures of different constructs. Validity is determined through empirical evidence over many studies, and is not an all-or-none concept. Factors like history, maturation, testing, and selection can threaten a test's validity if not controlled.
Experimental research aims to determine cause-and-effect relationships by manipulating an independent variable and observing its impact on a dependent variable. Key characteristics include comparing groups, one receiving a treatment and one not; manipulating the independent variable; and random assignment to control for extraneous variables. True experiments use random assignment, while quasi-experiments employ other techniques like matching. Various experimental designs differ in their ability to control threats to internal validity like history, maturation, testing, instrumentation, regression, selection, mortality, and interaction effects. Factorial designs allow investigation of interactions between variables.
The document discusses experimental research methods. It defines experimental research as applying treatments to groups and measuring their effects. It describes key aspects of experimental design including independent and dependent variables, as well as threats to internal and external validity like history, maturation, and selection bias. Finally, it outlines different experimental designs like single group, parallel group, and rotation group designs and the steps involved in conducting experimental research.
This document outlines an experimental research methods assignment for a group of students at Addis Ababa University College of Veterinary Medicine and Agriculture. It discusses key aspects of experimental design including objectives, variables, validity, types of designs, and potential sources of invalidity. The group's assignment is to design an experiment and address factors such as controls, randomization, measurements, and data analysis. Attention to these elements in the planning stage can help produce reliable and valid experimental results.
True experimental research designs aim to establish causal relationships. They have four key elements: manipulation of the independent variable, use of control groups, random assignment of subjects to conditions, and random selection of subjects. Randomized controlled trials are a type of true experiment that are considered the gold standard for determining cause and effect. Common true experimental designs include pre-test post-test control group designs, post-test only control group designs, and Solomon four-group designs.
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.
This document provides guidance on developing the methodology section of a research proposal. It discusses including descriptions of the research type (qualitative, quantitative, mixed), population and sampling method, and data collection and analysis tools and procedures. For the research type, the population should be defined along with the sampling strategy and sample size. Common data collection methods include surveys, interviews, and experiments. It is important to explain why the chosen methods are appropriate for answering the research question. The methodology allows readers to evaluate the reliability and validity of the study.
This document discusses key components of a research methodology section, including data collection methods, analysis approaches, population and sampling. It explains that the methodology section outlines the research design and allows readers to evaluate the study. It provides examples of elements to include, such as describing the research type as qualitative or quantitative, defining the population and sampling approach, and detailing the specific methods and tools used for data collection and analysis. The methodology provides transparency and validity to the research process.
This document discusses key elements in research design including causation, units of analysis, and time. It addresses causation in social science research and the criteria for determining causality. The four types of validity threats - statistical conclusion, internal, external, and construct validity - are summarized. Different units of analysis like individuals, groups, organizations, and social artifacts are also outlined. Finally, the document contrasts cross-sectional and longitudinal research, including trends, cohorts, panels, and how retrospective studies can approximate longitudinal data.
This document discusses single factor experimental research design. It describes the significant properties of randomization and manipulation of a single independent variable with at least two levels. It outlines types of single factor designs including between-subject and within-subject designs. It discusses threats to internal validity such as maturation and instrumentation. The document also notes ethical issues and advantages/limitations of this research design. Finally, it summarizes two examples of single factor experimental studies conducted in Pakistan.
This document discusses and compares various study designs used in medical research, including observational studies like case reports, case series, case-control studies, and cohort studies as well as experimental studies like randomized controlled trials. It provides descriptions of each study design along with their pros and cons. For example, it notes that case reports are useful for raising hypotheses but very rare to use to make statements of causation, while randomized controlled trials allow for control of therapy but have ethical and cost issues.
This presentation by John E. Kwoka, Neal F. Finnegan Distinguished Professor of Economics, Northeastern University, was made during the discussion “Ex-post Assessment of Merger Remedies” held at the 22nd meeting of the OECD Global Forum on Competition on 8 December 2023. More papers and presentations on the topic can be found out at oe.cd/eamr.
This presentation was uploaded with the author’s consent.
This document discusses key concepts in operationalizing and measuring variables in social science research. It covers how concepts are abstract mental representations that must be defined and measured concretely through operationalization. Operationalization involves developing observable indicators and dimensions of concepts. Measurement then assigns numerical or categorical values to those indicators. The document emphasizes creating exhaustive and mutually exclusive measurement categories and discusses different levels of measurement. It also outlines criteria for ensuring quality in measurement, including reliability, validity, and using composite measures and indexes.
Chapter 2
Study Designs
Learning Objectives
• List and define the components of a good
study design
• Compare and contrast observational and
experimental study designs
• Summarize the advantages and disadvantages
of alternative study designs
Learning Objectives
• Describe the key features of a randomized
controlled trial
• Identify the study designs used in public health
and medical studies
Study Designs
• Observational Studies
– Case-series study
– Cross-sectional (prevalence) survey
– Case-control study
– Cohort study
• Experimental Studies
– Randomized Controlled (Clinical) Trial
Inferences
• Observational studies – inferences limited to descriptions
and associations; with carefully designed analysis can
make stronger inferences (statistical adjustment)
• Experimental studies – cause and effect
In ALL studies – need careful definition of disease
(outcome) and exposure (risk factor)
Which Design is Best
• Depends on the study question
• What is current knowledge on topic
• How common is disease (and risk factors)
• How long would study take, what are costs
• Ethical issues
Case Report/Case Series
• Observational study
• Case report: Detailed report of specific
features of case
• Case series: Systematic review of common
features of a small number of cases
• Advantage: Cost-efficient
• Disadvantages: No comparison group, no
specific research question
Case-Series
• Simplest design – description of interesting
observations in a small number of individuals
• Usually case-series do not involve control patients
(i.e., patients free of disease)
• Usually lead to generation of hypotheses for more
formal testing
• Criticisms: not planned – no research hypotheses
Case-Series
• Gottleib (1981) studied 5 young homosexual
men with rare form of pneumonia and other
unusual infections
• Initial report was followed by more series (26
cases in NY and CA; “cluster” in southern CA;
34 cases among Haitians, etc.)
• Condition termed AIDS in 1982
Cross-Sectional Survey
• Observational study conducted at a point in
time
• Advantages: Cost-efficient, easy to implement,
ethical
• Disadvantages: No temporal information, non-
response bias
Cross-Sectional Survey
• Is there an association between diabetes and
cardiovascular disease (CVD)?
Patients
with
Diabetes
Patients without
Diabetes
Patients with
CVD
Prospective Cohort Study
• Observational study involving a group (cohort)
of individuals who meet inclusion criteria
followed prospectively in time for risk factor
and outcome information
• Advantages: Can assess temporal relationships
• Disadvantages: Need large numbers for rare
outcomes, confounding
Cohort Study
• Is there an association between hypertension and
cardiovascular disease?
CVD
Hypertension
No CVD
Cohort
CVD
No Hypertension
No CVD
Study Start Time
Cohort Studies
• Identify a group of individuals that meet
inclusion crit ...
Sardar CK DPT MSPT EBP Lecture 3 Part 1.pptxChangezKhan33
This document discusses different types of evidence that can be used to evaluate clinical interventions. It begins by describing clinical observation and the limitations of relying only on observation due to potential confounding variables. It then discusses different types of clinical research designs including case reports, case series, controlled trials, randomized trials, and systematic reviews. Randomized trials and systematic reviews are considered the best evidence as they aim to control for bias. The document concludes by noting while these designs provide quantification of effects, they may neglect patients' experiences, requiring different research approaches.
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.
Random control trial RCT community medicine .pptxAkshayRaj781072
The document discusses randomized controlled trials (RCTs), which are considered the gold standard for evaluating the effectiveness of medical interventions. It provides definitions of key RCT concepts like randomization, blinding, and intention-to-treat analysis. RCTs follow a strict protocol and involve randomly assigning participants to experimental and control groups, intervening, following up, and assessing outcomes while limiting bias. Well-conducted RCTs can establish whether medical treatments, devices, or services are efficacious compared to alternatives.
Adlt673 session 5_quantitative_validity_practicatility - class 5tjcarter
This document discusses research design and methodology. It begins by introducing different types of research designs, including experimental and non-experimental. It then covers key aspects of research such as developing hypotheses, defining variables, and establishing validity. Specific challenges of classroom-based research are also addressed. The document provides guidance on selecting an appropriate research design based on the study context and limitations. It emphasizes that every design has tradeoffs, and the best approach depends on the research question and constraints.
Factors that influence internal and external validity of.pptxAnanthiD6
Internal validity refers to whether the observed effects in an experiment can be attributed to the manipulation of the independent variable rather than other factors. Key factors influencing internal validity include controlling extraneous variables, randomization, experimental design, pre-testing and post-testing, placebo effects, and blinding. External validity concerns the generalizability of findings to other populations, settings, and times. Factors impacting external validity include population characteristics, sampling method, setting and context, timeframe, ecological validity, and cross-cultural considerations. Balancing internal and external validity is often a trade-off, so researchers must design experiments to achieve the right balance based on their research goals.
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
This document provides an overview of quantitative research methods. It defines quantitative research as a formal, objective, and systematic process used to generate information. The main types of quantitative research described are descriptive research, correlational research, quasi-experimental research, and experimental research. Experimental research aims to determine cause-and-effect relationships through controlled manipulation of variables and random assignment to groups. The steps of the quantitative research process include defining the problem, reviewing literature, identifying variables, collecting and analyzing data, and reporting results.
Here are some key points to consider in your discussion:
- Given the complexity of the project operating in a weak health system with resistant communities, a complexity-aware approach would be well-suited to understand the relationships between actors and pathways of change over time.
- Mixed methods would allow triangulation between qualitative data to understand relationships and pathways of change with quantitative data to measure outcomes. Starting with qualitative data collection in year 1 could help develop appropriate indicators for year 2.
- Quasi-experimental methods like a comparison pre-post design could measure outcomes but selection bias may be difficult to control for given the scale and nature of the intervention. Qualitative data would help understand any differences observed.
- Using a participatory
This document discusses the different types of validity in psychological testing: face validity, content validity, criterion validity (including predictive and concurrent validity), and discriminant validity. It provides examples for each type of validity. Criterion validity refers to how a test correlates with other measures of the same construct. Discriminant validity shows a test does not correlate with measures of different constructs. Validity is determined through empirical evidence over many studies, and is not an all-or-none concept. Factors like history, maturation, testing, and selection can threaten a test's validity if not controlled.
Experimental research aims to determine cause-and-effect relationships by manipulating an independent variable and observing its impact on a dependent variable. Key characteristics include comparing groups, one receiving a treatment and one not; manipulating the independent variable; and random assignment to control for extraneous variables. True experiments use random assignment, while quasi-experiments employ other techniques like matching. Various experimental designs differ in their ability to control threats to internal validity like history, maturation, testing, instrumentation, regression, selection, mortality, and interaction effects. Factorial designs allow investigation of interactions between variables.
The document discusses experimental research methods. It defines experimental research as applying treatments to groups and measuring their effects. It describes key aspects of experimental design including independent and dependent variables, as well as threats to internal and external validity like history, maturation, and selection bias. Finally, it outlines different experimental designs like single group, parallel group, and rotation group designs and the steps involved in conducting experimental research.
This document outlines an experimental research methods assignment for a group of students at Addis Ababa University College of Veterinary Medicine and Agriculture. It discusses key aspects of experimental design including objectives, variables, validity, types of designs, and potential sources of invalidity. The group's assignment is to design an experiment and address factors such as controls, randomization, measurements, and data analysis. Attention to these elements in the planning stage can help produce reliable and valid experimental results.
True experimental research designs aim to establish causal relationships. They have four key elements: manipulation of the independent variable, use of control groups, random assignment of subjects to conditions, and random selection of subjects. Randomized controlled trials are a type of true experiment that are considered the gold standard for determining cause and effect. Common true experimental designs include pre-test post-test control group designs, post-test only control group designs, and Solomon four-group designs.
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.
This document provides guidance on developing the methodology section of a research proposal. It discusses including descriptions of the research type (qualitative, quantitative, mixed), population and sampling method, and data collection and analysis tools and procedures. For the research type, the population should be defined along with the sampling strategy and sample size. Common data collection methods include surveys, interviews, and experiments. It is important to explain why the chosen methods are appropriate for answering the research question. The methodology allows readers to evaluate the reliability and validity of the study.
This document discusses key components of a research methodology section, including data collection methods, analysis approaches, population and sampling. It explains that the methodology section outlines the research design and allows readers to evaluate the study. It provides examples of elements to include, such as describing the research type as qualitative or quantitative, defining the population and sampling approach, and detailing the specific methods and tools used for data collection and analysis. The methodology provides transparency and validity to the research process.
This document discusses field observation as a method of data collection in criminal justice research. It involves directly observing phenomena in their natural settings to obtain qualitative and/or quantitative data. Key points covered include defining field observation, its use for understanding settings, behavior and events, different roles for observers, purposive sampling techniques used, methods for recording observations, linking observations to other data sources, examples of shoplifting and seatbelt use studies, and strengths and weaknesses of the method.
This document discusses qualitative interviewing techniques for gathering data in criminal justice studies. It covers different types of interviews like structured, semi-structured, and unstructured interviews. Focus groups are also discussed. The document provides guidance on designing interview questions, gaining access to participants, conducting interviews, recording data, analyzing qualitative data through coding and identifying themes, and ensuring rigor and quality.
This document discusses survey research methods. It defines survey research as administering questionnaires systematically to a sample population to describe or explore larger populations. It describes different question formats, administration methods like mail/phone/internet surveys, and considerations for designing valid and unbiased surveys. The strengths of surveys are their utility for describing large groups, while weaknesses include superficial coverage of complex topics.
Here are some key points I would make about the strengths and weaknesses of snowball sampling:
Strengths:
- Can be useful for hard-to-reach populations where a sampling frame does not exist. Referrals can help reach hidden groups.
- Low cost since it relies on referrals rather than developing a sampling frame.
Weaknesses:
- Results cannot be generalized to the larger population since it is a non-probability sample.
- Prone to bias if the initial referrals are not representative of the target population. The sample can become quite homogeneous.
- Over-representation of close social connections since people tend to know and refer others like themselves.
- Difficult to determine the sampling error
This document discusses survey research methods. It defines survey research as administering questionnaires systematically to a sample population to describe or explore larger populations. It describes different question formats, administration methods like mail, phone and in-person interviews, and considerations for designing valid and unbiased surveys. The document outlines best practices for survey research and compares strengths and weaknesses of different administration approaches.
This document discusses different approaches to measuring crime. It outlines various measures including crimes known to police through records like the Uniform Crime Reports, and crimes measured through victimization surveys like the National Crime Victimization Survey. These measures have different units of analysis, purposes for data collection, and strengths and limitations in assessing the true prevalence of crime. The document emphasizes that no single measure can capture all crime due to imperfections, and different measures are needed to satisfy different criteria.
The document discusses key concepts in measurement for social research:
- Concepts are abstract mental representations that must be operationalized through concrete empirical procedures to enable measurement.
- Variables can be measured at different levels from nominal to ratio.
- Reliability and validity are important criteria for measurement quality, and composite measures can improve reliability and validity by combining multiple individual measures into a single index.
This document discusses concepts, operationalization, and measurement. It covers defining concepts, linking concepts to observations through indicators and dimensions, and clarifying concepts to enable measurement. Concepts are mental representations that group similar observations but do not exist in reality. Measurement involves linking concepts to direct and indirect observables or theoretical constructs through operational definitions that specify how to measure indicators of a concept. Clarifying abstract concepts is key to accurate measurement in research.
This document provides information about an upcoming social work research methods class. It includes the following:
- Details about assignments and guest speakers for week 8, including a literature review draft being graded and a guest speaker on social work research.
- An overview of quantitative and qualitative research methods and their differences.
- The importance of research design for social workers to operate from an evidence-based knowledge base and justify their work.
- Examples of research methods used in social work like surveys, program evaluations, and needs assessments.
This document provides information about an upcoming social work research methods course. It includes details about assignments, guest speakers, and exam dates. The guest speaker, Professor Stamp, will discuss social work research and answer questions. She covers topics like how social workers assess interventions and policies using data collection and research methods like quantitative and qualitative research. The importance of research design for social workers is emphasized, as they must use evidence to improve lives. Common social work research methods mentioned include surveys, program evaluations, and needs assessments.
This document provides information about housekeeping items for a social work research methods class. It outlines due dates for assignments, an upcoming guest speaker on social work research, and dates for a literature review and midterm exam. It also summarizes a guest lecture on the importance of research for social workers to understand populations, evaluate interventions, and inform policies using evidence and data. The lecture discusses quantitative and qualitative research methods used in social work, including surveys, program evaluations, and needs assessments.
This document discusses key elements of research design, including causation, units of analysis, and the time dimension. It explains that causation in social science is probabilistic and there are two models of explanation - ideographic and nomothetic. The main units of analysis are individuals, groups, organizations, and social artifacts. Researchers must avoid ecological and individualistic fallacies by properly matching units of analysis. Research can examine a single point in time via cross-sectional studies or observe changes over time through longitudinal, trend, cohort, and panel studies. Retrospective studies can sometimes approximate longitudinal designs.
This document discusses ethics in criminal justice research. It describes special ethical issues like discovering misconduct or influencing crime. It discusses how informed consent and institutional review boards (IRBs) address these issues. IRBs were established by the National Research Act to review research proposals and ensure the safety, confidentiality and welfare of subjects. They determine if research includes necessary safeguards.
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