Can fuel-efficiency be increased with different rubber compounds for automobile tires? Answering the question requires coming up with a research strategy that effectively answers the question being asked. This is obvious in theory; in practice, there are many research strategies that fail to answer the question. For example, all three of the questions posed above could be answered simply by administering the drug, conducting more flash-card reading quizzes in KI or trying out a different rubber compound.
If cancers then spread slower, reading outcomes improved and mileage rates went up, this may show that each of these approaches works. But in each case, there's a fundamental flaw in the research design that makes relying on a favorable outcome an unreliable indication that any of these things work. Take the cancer drug, for example. If you know that the time from diagnosis to mortality for the cancer is 4. First of all, the research design fails to match the total U. If your research hospital's patients differ in profile from the general patient population for this cancer, that could account for the increased longevity.
Richer patients, for example, are usually diagnosed earlier than poorer patients. This affects outcomes profoundly. Secondly, without administration of the drug to one patient group and administration of a placebo to another group of patients matched as closely as possible to the first, while you can say that longevity increased, you have no way of knowing that the drug is what made the difference. Even if you tried to create a patient group that matched a larger population and then noticed that outcomes improved, without a control group, how do you know that it wasn't just the psychological boost that came with being enrolled that improved outcomes?
The notorious "placebo effect" could account for all of it. It's widely known that patient outcomes often improve when a placebo is administered, which proves that the mind is a powerful thing, but not that the placebo is an effective drug for treating cancer.
There are many different experimental research design strategies. Here are a few of the most common:. Other common design strategies subdivide test groups into subjects with similar profiles, or test two hypotheses simultaneously or test different subgroups with several tests administered in different orders. These criteria assure that the outcome of treatment results directly and exclusively from a defined variable.
Another criterion for a successful research design that's been increasingly influential in the 21st century. Perhaps the most egregious violation of that principle was the notorious Tuskegee "Study of Untreated Syphilis in the Negro Male," begun in and conducted over a 40 year period by the U.
Public Health Service on subjects exposed to syphilis, sometimes without their knowledge, and then lied to about placebo treatments that left them untreated. While the experiment itself was inexcusable, it eventually resulted in an increased awareness of science's responsibility for ethical experimental design. A similar emphasis on ethical experimental design has limited the number of research experiments involving animals in the 21st century. Testing for the effects of various cosmetics, for instance, some of them subsequently proven to be harmful or fatal to mammals, has decreased substantially worldwide and in some countries is now prohibited entirely.
I am a retired Registered Investment Advisor with 12 years experience as head of an investment management firm. I also have a Ph. Skip to main content. Researcher 4 Resume Format for Clinical Research. Obviously, we can never achieve this hypothetical situation. If we give the program to a group of people, we can't simultaneously not give it! So, how do we get out of this apparent dilemma? Perhaps we just need to think about the problem a little differently. What if we could create two groups or contexts that are as similar as we can possibly make them?
If we could be confident that the two situations are comparable, then we could administer our program in one and see if the outcome occurs and not give the program in the other and see if the outcome doesn't occur. And, if the two contexts are comparable, then this is like taking both forks in the road simultaneously! We can have our cake and eat it too, so to speak.
That's exactly what an experimental design tries to achieve. In the simplest type of experiment, we create two groups that are "equivalent" to each other. One group the program or treatment group gets the program and the other group the comparison or control group does not. In all other respects, the groups are treated the same. They have similar people, live in similar contexts, have similar backgrounds, and so on. Now, if we observe differences in outcomes between these two groups, then the differences must be due to the only thing that differs between them -- that one got the program and the other didn't.
OK, so how do we create two groups that are "equivalent"? The approach used in experimental design is to assign people randomly from a common pool of people into the two groups. The experiment relies on this idea of random assignment to groups as the basis for obtaining two groups that are similar. Then, we give one the program or treatment and we don't give it to the other.
We observe the same outcomes in both groups. The key to the success of the experiment is in the random assignment. In fact, even with random assignment we never expect that the groups we create will be exactly the same. How could they be, when they are made up of different people?
We rely on the idea of probability and assume that the two groups are " probabilistically equivalent " or equivalent within known probabilistic ranges. So, if we randomly assign people to two groups, and we have enough people in our study to achieve the desired probabilistic equivalence, then we may consider the experiment to be strong in internal validity and we probably have a good shot at assessing whether the program causes the outcome s.
But there are lots of things that can go wrong. We may not have a large enough sample. Or, we may have people who refuse to participate in our study or who drop out part way through.
Or, we may be challenged successfully on ethical grounds after all, in order to use this approach we have to deny the program to some people who might be equally deserving of it as others. Or, we may get resistance from the staff in our study who would like some of their "favorite" people to get the program. Or, they mayor might insist that her daughter be put into the new program in an educational study because it may mean she'll get better grades.
Types of Experimental Research. The following module discusses the types of experimental research and focuses on the types of research designs commonly used in true experimental research. Learning Objectives: List the three broad categories of experimental research. Describe the different kinds of true experimental research design.
Mar 26, · Effective experimental research design always answers a specific question in a way that controls for differences in treatment populations and for other differences, usually by creating an experimental group and a control group, testing both populations before and after completion of the experiment.
The research design is chosen based on a range of factors. Important factors when choosing the design are feasibility, time, cost, ethics, measurement problems and what you would like to test. The design of the experiment is critical for the validity of the results. In experimental research, researchers use three basic experiment designs: pre-experiment, true experiment and quasi-experiment, as explained in the section below. Pre-experimental research: In pre-experimental research, researchers follow basic experimental steps but do not use a control group.
experimental design a research design that eliminates all factors that influence outcome except for the cause being studied (independent variable). All other factors are controlled by randomization, investigator-controlled manipulation of the independent variable, and control of the study situation by the investigator, including the use of. The goal of experimental research is to explain effects and determine a causal relation between two variables. Experimental researchers attempt to answer a research question that asks what effects one variable has on another variable. For example, experimental research may be used to answer the.