What research design aims to determine a cause from already existing effects quizlet?
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Published on July 31, 2020 by Lauren Thomas. Revised on July 21, 2022. 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. Quasi-experimental design is a useful
tool in situations where true experiments cannot be used for ethical or practical reasons. There are several common differences between true and quasi-experimental designs. Every few
months, patients fill out a sheet describing their symptoms to see if the new treatment produces significantly better (or worse) effects than the standard one. However, for ethical reasons, the directors of the mental health clinic may not give you permission to randomly assign their patients to treatments. In this case, you cannot run a true experiment. Instead, you can use a quasi-experimental design. You can use these pre-existing groups to study the symptom progression of the patients treated with the new therapy versus those receiving the standard course of treatment. Although the groups were not randomly assigned, if you properly account for any systematic differences between them, you can be
reasonably confident any differences must arise from the treatment and not other confounding variables. Many types of quasi-experimental designs exist. Here we explain three of the most common types: nonequivalent groups design, regression discontinuity, and natural experiments. Nonequivalent groups designIn nonequivalent group design, the researcher chooses existing groups that appear similar, but where only one of the groups experiences the treatment. In a true experiment with random assignment, the control and treatment groups are considered equivalent in every way other than the treatment. But in a quasi-experiment where the groups are not random, they may differ in other ways—they are nonequivalent groups. When using this kind of design, researchers try to account for any confounding variables by controlling for them in their analysis or by choosing groups that are as similar as possible. This is the most common type of quasi-experimental design. Example: Nonequivalent groups designYou hypothesize that a new after-school program will lead to higher grades. You choose two similar groups of children who attend different schools, one of which implements the new program while the other does not.By comparing the children who attend the program with those who do not, you can find out whether it has an impact on grades. Regression discontinuityMany potential treatments that researchers wish to study are designed around an essentially arbitrary cutoff, where those above the threshold receive the treatment and those below it do not. Near this threshold, the differences between the two groups are often so minimal as to be nearly nonexistent. Therefore, researchers can use individuals just below the threshold as a control group and those just above as a treatment group. Example: Regression discontinuitySome high schools in the United States are set aside for high-achieving students, who must exceed a certain score on a test to be allowed to attend. Those who pass this test most likely differ systematically from those who do not.However, since the exact cutoff score is arbitrary, the students near the threshold—those who just barely pass the exam and those who fail by a very small margin—tend to be very similar, with the small differences in their scores mostly due to random chance. You can therefore conclude that any outcome differences must come from the school they attended. To test the impact of attending a selective school, you can study the long-term outcomes of these two groups of students (those who barely passed and those who barely failed). Natural experimentsIn both laboratory and field experiments, researchers normally control which group the subjects are assigned to. In a natural experiment, an external event or situation (“nature”) results in the random or random-like assignment of subjects to the treatment group. Even though some use random assignments, natural experiments are not considered to be true experiments because they are observational in nature. Although the researchers have no control over the independent variable, they can exploit this event after the fact to study the effect of the treatment. Example: Natural experiment The Oregon Health Study is one of the most famous natural experiments. In 2008, the state of Oregon decided to expand enrollment in Medicaid, America’s low-income public health insurance program, to more low-income adults.However, as they could not afford to cover everyone who they deemed eligible for the program, they instead allocated spots in the program based on a random lottery. Researchers were able to study the impact of the program by using the enrolled individuals as a randomly assigned treatment group, and the others who were eligible but did not succeed in the lottery as a control group. What can proofreading do for your paper?Scribbr editors not only correct grammar and spelling mistakes, but also strengthen your writing by making sure your paper is free of vague language, redundant words and awkward phrasing.  See editing example When to use quasi-experimental designAlthough true experiments have higher internal validity, you might choose to use a quasi-experimental design for ethical or practical reasons. EthicalSometimes it would be unethical to provide or withhold a treatment on a random basis, so a true experiment is not feasible. In this case, a quasi-experiment can allow you to study the same causal relationship without the ethical issues. The Oregon Health Study is a good example. It would be unethical to randomly provide some people with health insurance but purposely prevent others from receiving it solely for the purposes of research. However, since the Oregon government faced financial constraints and decided to provide health insurance via lottery, studying this event after the fact is a much more ethical approach to studying the same problem. PracticalTrue experimental design may be infeasible to implement or simply too expensive, particularly for researchers without access to large funding streams. At other times, too much work is involved in recruiting and properly designing an experimental intervention for an adequate number of subjects to justify a true experiment. In either case, quasi-experimental designs allow you to study the question by taking advantage of data that has previously been paid for or collected by others (often the government). Advantages and disadvantagesQuasi-experimental designs have various pros and cons compared to other types of studies.
Frequently asked questions about quasi-experimental designsWhat is random assignment? In experimental research, random assignment is a way of placing participants from your sample into different groups using randomization. With this method, every member of the sample has a known or equal chance of being placed in a control group or an experimental group. Cite this Scribbr articleIf you want to cite this source, you can copy and paste the citation or click the “Cite this Scribbr article” button to automatically add the citation to our free Citation Generator.
Is this article helpful?You have already voted. Thanks :-) Your vote is saved :-) Processing your vote... What research design addresses determination of cause and effect?Experimental research allows the researcher to control the situation. In so doing, it allows researchers to answer the question, “what causes something to occur?” Permits the researcher to identify cause and effect relationships between variables and to distinguish placebo effects from treatment effects.
Which type of research design is able to claim that it can identify cause and effect relationships?Experimental research, often called true experimentation, uses the scientific method to establish the cause-effect relationship among a group of variables that make up a study.
Which research method Reveals cause and effect?The only method that will establish a cause-and-effect relationship is an experimental research design. A true experiment must feature a control group as one of the experimental groups, along with random sampling from the population and random assignment of the study subjects to the experimental groups.
Which of the following study designs focuses on finding a cause and effect relationship?experimental research
attempts to establish cause- effect relationships among the variables. These types of design are very similar to true experiments, but with some key differences.
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