RESEARCH: Quasi Experimental Research Design
Summary
TLDRThis video script from the English Simplified channel delves into quasi-experimental research design, a method aiming to establish cause and effect without random assignment. It's used when true experiments are impractical or unethical. The script outlines five types of designs, including post-test only, pre-test post-test, interrupted time series, and switching replications, each with unique procedures and data analysis methods. The goal is to provide clarity on when and how to apply these designs in real-world settings.
Takeaways
- 🧪 Quasi-experimental designs aim to establish cause and effect relationships, similar to true experiments, but without the use of random assignment.
- 🔄 Unlike true experiments, quasi-experiments do not use random sampling or random assignment, which is a method of placing participants into different treatment groups randomly.
- 🚫 Quasi-experimental designs are often used when it is unethical or impractical to conduct a true experiment, typically in field settings where random assignment is difficult.
- 👥 Quasi-experiments involve at least two groups: a control group and an experimental group, but participants are not selected through random sampling.
- 📝 There are five main types of quasi-experimental designs: post-test only non-equivalent groups, pre-test post-test non-equivalent groups, interrupted time series with non-equivalent groups, pre-test post-test with switching replication, and switching replication with treatment removal.
- 📊 Post-test only non-equivalent groups design involves a treatment given to one group and a comparison of post-tests between the experimental and control groups.
- 📉 Pre-test post-test non-equivalent groups design measures the dependent variable before and after treatment, comparing means or using statistical tests like t-test for analysis.
- 🕒 Interrupted time series design involves measurements taken at intervals over time, both before and after an intervention in non-equivalent groups.
- 🔄 Pre-test post-test with switching replication administers treatment to one group first, then switches to the control group, analyzing the dependent variable's changes.
- 🔄 Switching replication with treatment removal design involves phases where treatment is given and then removed for one group while the other group receives it later, analyzing the effects of treatment presence and absence.
- 🔑 The key difference between quasi-experimental and true experimental designs is the absence of random selection and assignment in quasi-experiments, which affects the internal validity of the research.
Q & A
What is the main difference between a quasi-experimental design and a true experiment?
-The main difference is that a quasi-experimental design does not rely on random assignment of subjects to groups, unlike a true experiment which uses random sampling and assignment.
Why is quasi-experimental research used instead of a true experiment?
-Quasi-experimental research is used in situations where it would be unethical or impractical to run a true experiment, often in field settings where random assignment is difficult or impossible.
What are the two groups typically involved in quasi-experimental designs?
-The two groups typically involved are the control group and the experimental group.
How does the post-test only non-equivalent groups design differ from the pre-test post-test non-equivalent groups design?
-In the post-test only non-equivalent groups design, there is no pre-test, and only the experimental group receives the treatment before the post-test. In contrast, the pre-test post-test non-equivalent groups design includes both a pre-test and a post-test for both groups, with the experimental group receiving the treatment in between.
What is an interrupted time series design with non-equivalent groups?
-It is a variant of the pre-test post-test design where measurements are taken at intervals over time, both before and after an intervention in two or more non-equivalent groups.
How is the pre-test post-test design with switching replication applied?
-In this design, a pre-test is administered to both groups, then one group receives a treatment while the other does not. After assessing the dependent variable again, the treatment is added to the control group, and the dependent variable is assessed one last time.
What is the purpose of the switching replication with treatment removal design?
-This design is used to assess the effects of both the introduction and removal of a treatment by administering it to one group first, then to the other group, and analyzing the dependent variable's changes over time.
How is data analyzed in a post-test only non-equivalent groups design?
-The data is analyzed by comparing the post-test results of the two groups, which includes the experimental group that received the treatment and the control group that did not.
What statistical analysis is often used in the pre-test post-test non-equivalent groups design?
-The data is often analyzed using a t-test to compare the mean of the post-test results between the two groups.
How does the interrupted time series design with non-equivalent groups help in understanding the impact of an intervention?
-This design helps by providing a series of measurements over time, allowing for the analysis of trends and the impact of the intervention at different points in time for both the experimental and control groups.
What is the significance of random sampling and random assignment in true experimental research?
-Random sampling and assignment are crucial in true experimental research to reduce bias and ensure that the results can be generalized to the population, establishing a stronger cause-and-effect relationship.
Outlines
🔬 Introduction to Quasi-Experimental Research
This paragraph introduces the concept of quasi-experimental research design, which aims to establish a cause-and-effect relationship without the use of random assignment. It distinguishes quasi-experiments from true experiments by explaining the lack of random sampling and assignment in the former. The paragraph outlines the structure of the discussion, which includes understanding what quasi-experimental research is, its applications, how it's conducted, its types, and data analysis methods. It sets the stage for an in-depth exploration of quasi-experimental designs in various contexts where random assignment is not feasible.
📚 When to Use Quasi-Experimental Design
This section delves into the specific situations where quasi-experimental designs are most applicable, particularly when conducting a true experiment would be unethical or impractical. It highlights the use of quasi-experiments in field settings and explains the composition of the sample into control and experimental groups without the benefit of random selection. The paragraph emphasizes the ethical considerations and practical constraints that lead researchers to opt for quasi-experimental designs over true experiments.
🔍 Application and Types of Quasi-Experimental Designs
The paragraph discusses the application of quasi-experimental designs and outlines their various types. It describes five distinct types: post-test only non-equivalent groups design, pre-test post-test non-equivalent groups design, interrupted time series design with non-equivalent groups, pre-test post-test design with switching replication, and switching replication with treatment removal design. Each design is briefly explained in terms of its procedure, from pre-testing to post-testing, and the treatment administration differences between experimental and control groups. The paragraph provides a foundation for understanding how each design facilitates the comparison and analysis of data to draw meaningful conclusions.
📈 Detailed Examination of Quasi-Experimental Design Procedures
This paragraph provides a detailed examination of the procedures involved in different types of quasi-experimental designs. It explains the step-by-step process for each design, from administering pre-tests to post-tests and the timing of treatment administration. The paragraph clarifies how data is analyzed in each design, emphasizing the importance of comparing post-test results and using statistical methods like t-tests to infer causality. It offers a comprehensive look at the methodology behind quasi-experimental research, showcasing the nuances of each design and their respective data analysis techniques.
📝 Conclusion and Summary of Quasi-Experimental Research
The final paragraph summarizes the key points discussed in the video script about quasi-experimental research design. It reiterates the main difference between quasi-experiments and true experiments, which is the absence of random selection and assignment in the former. The paragraph lists the five types of quasi-experimental designs and briefly describes the unique features of each, such as the presence or absence of pre-tests, the timing of treatments, and the structure of data analysis. The summary serves to reinforce the understanding of quasi-experimental designs and sets the stage for future discussions on true experimental and factorial designs.
Mindmap
Keywords
💡Quasi-experimental design
💡Cause and effect
💡Random assignment
💡Non-equivalent groups
💡Pre-test and post-test
💡Interrupted time series design
💡Switching replication
💡Treatment removal
💡Ethical considerations
💡Field settings
💡Statistical analysis
Highlights
Introduction to quasi-experimental research design, a method to establish cause and effect without random assignment.
Difference between quasi-experimental and true experiments, particularly the lack of random sampling and assignment in the former.
Quasi-experimental design's resemblance to true experiments but with non-random criteria for group assignment.
Ethical and practical limitations that make quasi-experimental design preferable over true experiments.
Quasi-experiments are often conducted in field settings where random assignment is not feasible.
Existence of two main groups in quasi-experimental designs: control and experimental.
Explanation of the five types of quasi-experimental designs and their unique applications.
Description of the post-test only non-equivalent groups design and its procedure.
The pre-test post-test non-equivalent groups design, including its steps and data analysis method.
Interrupted time series design with non-equivalent groups, focusing on measurements over time.
Pre-test post-test design with switching replication and its iterative treatment application process.
Switching replication with treatment removal design, detailing the phases and analysis of data.
Summary of the key features of the post-test only non-equivalent groups design.
Summary of the pre-test post-test design with non-equivalent groups, emphasizing statistical analysis.
Summary of the interrupted time series design, highlighting the importance of time-based measurements.
Overview of the pre-test post-test design with switching replication, focusing on treatment administration and analysis.
Final summary of the quasi-experimental research design, its types, and their respective procedures and analyses.
Announcement of upcoming topics on true experimental research design and factorial design.
Transcripts
hi there how are you doing welcome back to english simplified channel as we had already
discussed what experimental research is and one of its type that is pre-experimental so in this
session we are discussing its second type that is quasi-experimental research design
in order to understand this easily so i divide the discussion into a what is quasi-experimental
b when is it used c how is it applied d what are its types and how its data is analyzed
well are you ready let's get started
part a what is quasi-experimental like a true experiment a quasi-experimental design
aims to establish a cause and effect relationship between an independent and dependent variable
however unlike a true experiment a quasi-experiment does not rely on random
assignment instead subjects are assigned to groups based on non-random criteria
so in conclusion this quasi-experimental research is research that resembles experimental research
but is not true experimental research because it doesn't use random assignment in which it is a way
of placing participants from your sample into different treatment groups using randomization
as you have to know a true experimental should apply random sampling and random assignment
in selecting the sample random sampling also called probability sampling or random selection
is a way of selecting members of a population to be included in your study while you use random
assignment to place participants or sample into the control or experimental group in fact in
quasi-experimental these procedures aren't applied that's why it's named as quasi-experimental design
well now let's continue to part b when is quasi-experimental used
quasi-experimental design is most useful in situations where it would be unethical or
impractical to run a true experiment in other words quasi experiments are most likely to be
conducted in field settings in which random assignment is difficult or impossible bear in
mind quasi-experimental has two groups of sample namely control and experimental groups but this
sample on selected by random sampling and random assignment as i have already mentioned it before
all right and this is part see how is quasi-experimental applied as there are
some types of quasi-experimental and the way they are applied is different for each type
then to answer this question we have to discuss it type by type
and continue to the next part that is party what are its types and how a stator is analyzed
well the types of quasi-experimental are such as one post-test only non-equivalent groups design
two pre-test post-test non-equivalent groups design three interrupted time series design
with non-equivalent groups four pre-test post test design with switching replication
and five switching replication with treatment removal design all right let's see one by one
number one post-test only non-equivalent groups design
in this design participants in one group are exposed to treatment a non-equivalent or control
group is not exposed to the treatment and then the two groups are compared what does this mean
let's see the procedure post test only non-equivalent groups design has two groups
of sample they are experimental and control groups treatment is only given to the experimental group
or the control group is with no treatment after that the two groups are tested which is
called post test so it means there is only post test in this design or this design is without
pre-test then finally the data is analyzed by comparing the post-test of the two groups
now let's see and discuss the second type of quasi-experimental that is 2. pre-test
post-test non-equivalent groups design in a pre-test post-test design the dependent
variable is measured once before the treatment is implemented and once after it is implemented let's
see its procedure this design also has two groups of sample they are control and experimental groups
the first step is to address pre-test to the two groups then it is continued by giving the
treatment to only experimental group having finished giving the treatment then the two
groups are tested once again with what it's called post test and to make the conclusion
then the data is analyzed by comparing the mean of the post-test of the two groups or
by statistical analysis of t-test okay now we're discussing the third type of quasi-experimental
that is three interrupted time series design with non-equivalent groups a variant of the pre-test
post test design is the interrupted time series design a time series is a set of measurements
taken at intervals over a period of time in addition the interrupted time series designed
with non-equivalent groups involves taking a set of measurements at intervals over a period of time
both before and after an intervention of interest in two or more non-equivalent groups
let's see how it is done or applied the first step is to give pre-test to the two groups
then treatment is given here you have to know the treatment given is by some periods of time
as in this example treatment is given each week for six months to the experimental group
while the control group doesn't receive the treatment after that
the two groups are post-tested and finally the data is analyzed to draw the conclusion
well the next type of quasi-experimental is pre-test post-test design with switching
replication in pre-test post-test design with switching replication
is done by using a pre-test post-test design with switching replication design
non-equivalent groups are administered a pre-test of the dependent variable
then one group receives a treatment while a non-equivalent control group does not receive a
treatment the dependent variable is assessed again and then the treatment is added to the control
group and finally the dependent variable is assessed one last time okay let's see it procedure
the first step is by addressing pretest to the two groups then treatment is firstly given to
the experimental group while for the control group is held off after that the two groups
are post-tested then the treatment is given to the control group after giving it the control group is
again post-tested and finally the conclusion is made by comparing and analyzing the data
and now we have come to last type of quasi-experimental
that is switching replication with treatment removal design
in a basic pre-test post-test design with switching replication the first group receives
a treatment and the second group receives the same treatment a little bit later on
while the initial group continues to receive the treatment all right let's see its procedure
this design at least has two phases for example a research is conducted in two phases in two weeks
so in phase one and week one both the experimental and control groups are
pre-tested then the treatment is firstly given to the experimental group while for the control
group is held off after that the two groups are tested again with a test namely post-test
then finally the data is analyzed and saved
next in phase 2 week 2 the treatment is stopped for experimental group while the control group
is now receiving the treatment after the treatment is done for the control group
again the two groups are post-tested and finally the data is analyzed to draw the conclusion
all right now let's make the conclusion and summary one a quasi-experiment is a
type of research design that attempts to establish a cause and effect relationship
the main difference with a true experiment is that the groups are not randomly selected and assigned
two there are five types of quasi-experiment designs that are between subjects and nature they
are one the post-test only non-equivalent groups design two the pre-test post-test design with
non-equivalent groups three the interrupted time series design with non-equivalent groups
four the pre-test post test design with switching replication and five the switching replication
with treatment removal design in post-test only non-equivalent groups design has two groups of
sample they are experimental and control groups treatment is only given to the experimental group
or the control group is with no treatment after that the two groups are tested which is called
post test so it means there is only post test in this design or this design is without pre-test
two the pre-test post test design with non-equivalent groups this design also
has two groups of sample they are control and experimental groups the first step is to address
pre-test to the two groups then it is continued by giving the treatment to only experimental group
having finished giving the treatment then the two groups are tested once again with
what it's called post-test and to make the conclusion then the data is analyzed
by comparing the mean of the post-test of the two groups or by statistical analysis of t-test
three the interrupted time series design with non-equivalent groups the first step is to give
pre-test to the two groups then treatment is given here you have to know the treatment given
is by some periods of time as in this example treatment is given each week for six months
to the experimental group while the control group doesn't receive the treatment after that
the two groups are post-tested and finally the data is analyzed to draw the conclusion
for the pre-test post-test design with switching replication the first step is by addressing
pre-test to the two groups then treatment is firstly given to the experimental group
while for the control group is held off after that the two groups are post-tested then the
treatment is given to the control group after giving it the control group is again post-tested
then finally the conclusion is made by comparing and analyzing the data
and the last type is number five the switching replication with treatment removal design
this design at least has two phases for example a research is conducted in two phases in two weeks
so in phase one and week one both the experimental and control groups are pre-tested
then the treatment is firstly given to the experimental group while for the control
group is held off after that the two groups are tested again with a test namely post test
then finally the data is analyzed and saved
next in phase 2 week 2 the treatment is stopped for experimental group while the control group
is now receiving the treatment after the treatment is done for the control group
again the two groups are post-tested and finally the data is analyzed to draw the conclusion
well that's at our discussion relating to quasi-experimental research design
hopefully this explanation has broadened your knowledge as we have already covered
pre-experimental research design and quasi-experimental research design
then our next topic of discussion will be true experimental research design and factorial
design by the way don't forget to support my channel by your subscribe thanks and tartare
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