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¶ … limiting a researcher's view of the problem are situational factors that can skew the results of her experiment, i.e., effects of pretesting, social threats, and group differences (Trochim, 2008, 188). External factors, such as possible sample size, can limit even the type of testing available to the researcher. As such, researchers have come up with a number of different types of designs over the years. This essay will compare and contrast two of these; experimental and quasi-experimental designs.
"Experimental designs are often touted as the most rigorous of all research designs" (Trochim, 2008, 186). What is so rigorous about them is that they are the strongest type of design in regards to their internal validity (Trochim, 2008, 186). This is because the basic form of the experimental design uses random assignment, or chance to group participants. In effect, this makes the two groups, if selected from...
This enables the researcher to actually "calculate the chance that the two groups will differ just because of the random assignment (that is, by chance alone)" (Trochim, 2008, 189).
The way that experimental designs control internal validity so well is a function of their structure. A simple experimental design called a two-group, posttest-only, randomized design uses random assignment to create two groups; one in which treatment is offered (for example), and one that receives no treatment at all. Posttesting is then performed. If the treatment group shows a different outcome than the no-treatment group, we might be able to conclude that the different outcome was a result of the treatment. We are confident in the experiment's internal validity because, since groups were assigned randomly, we know that the difference in…
Why would a researcher, who values internal validity, then choose a quasi-experimental design, that specifically lacks in internal validity? The reason is that experimental designs are not always the most effective. They're subject to social threats of internal validity, and have difficulties with external validity (Trochim, 2008, 188). An experimental design is "intrusive and difficult to carry out in most real-world contexts," and is basically an "artificial situation" created to "assess [a] causal relationship with high-internal validity." Resultingly, there are difficulties in generalizing the findings to the real world.
Alternatively, certain types of quasi-experimental designs are some "of the most intuitively sensible designs around" (Trochim, 2008, 210). This is because random selection is often not logical or possible. For example, say we wanted to understand the effects of a certain type of treatment on both developmentally disabled adults and adults that were not developmentally disabled. Random selection, or an experimental design, would be impossible here, because we already have our two groups; they're dictated by the difference.
The basic reasons one might choose an experimental design or a quasi-experimental design has to do with, I think, resources, and what exactly is being tested. I feel that there is no design that is "better" or "worse" -- applying those labels would not make any sense at all here, because every experiment has a different aim. What is good for one experiment may be bad for another. The most important thing, I feel, is simply to have an understanding of both, and the ability to employ each when necessary.
Quasi-Experimental Design on the Effect of TV Adverts on Children This study carries out the evaluation of a research titled "A quasi-experiment assessing the effectiveness of TV advertising directed to children" (Goldberg, 1990 p 445). The paper examines the extent the research hypotheses have been able to address the study. The paper also examines the research dependent variables and independent variables. Moreover, the study investigates the extent the author has adhered
Experimental Research Methods in Business Experimental Research Methods The author provides a survey of the literature illustrating applied experimental research methods in cross-sections of business and organization types. The advantages and disadvantages of the experimental research methods are discussed for each of the examples provided which run the gamut from depression-era agricultural economics to research conducted for the National Science Institute. While the article focuses on business research methods, the range of
E., contemporary or historical issues (Eisenhardt 1989; in Naslund, 2005); (3) the extent of control required over behavioral events in the research context (Yin 1994; as cited in Naslund, 2005); and (4) the researcher's philosophical stance, i.e., his/her understanding of the nature of social reality and how knowledge of that reality can be gained. (Naslund, 2005) Naslund (2005) states that qualitative research methods "primarily create meanings and explanations to research phenomena" and
Experimental Study Design and Intention to Treat Hepatitis C Virus (HCV) association with HIV Infection in Gay Men The population for this research will comprise of persons enrolled in one out of five CPCRA (Community Programs for Clinical Research on AIDS) studies at sixteen CPCRA facilities across America. The five researches will take the form of four randomized clinical trials (RCTs) for antiretroviral (ARV) therapy strategies and one natural history analysis of
Part 1 1. Explain the difference between the terms factors and treatments. Give an example Within an experimental setting, the term factor which is also referred to as an independent variable is a variable that is explanatory and can usually be manipulated by the one conducting the experiment. Every factor typically has different values meaning that there are two or more levels for the factor. On the other hand, treatment can be
social science researchers have a number of different types of research designs available to them, including observational studies, correlational research, developmental designs, survey research and experimental designs (Neuman, 2009). This paper reviews the literature concerning quantitative survey research and experimental designs to provide a comparison of their similarities and differences, including their respective processes for selecting an appropriate population sample. In addition, a description of a respective strength and