Types of Quasi-Experimental Design — Utility and Importance
The experimental and quasi-experimental designs refer to the research papers. While experimental designs mean the entirely controlled experiment, different types of quasi-experimental design may imply the lack of such control. For example, the experimental design is used in the psychological research paper where the researcher can lead the experimental group, its population, and actions of every member.
Types of quasi-experimental design are combined by the absence of one or several key features of a true design: control, random choice or random treatment. A quasi-experimental design may be applied in the majority of natural sciences where the members and factors cannot be fully controlled. For example, such design will be revealed in the research concerning smoking and lung cancer. What do you have to know in order to guess how many types of quasi-experimental design there is? It is good to learn about:
- How to differentiate the quasi and true experiments?
- Advantages and disadvantages of the quasi-experimental design.
- Wheat are the spheres of their applying?
At first, let’s consider the similarities and differences between true experiments and quasi-ones.
Here are some examples of common things that relate to the types of experiment:
- Every time the participants of the experiment are treated or act in a particular manner.
- The results of the experiment can be measured somehow.
- People who conduct the research can measure if the research outcome has differences from the research expectations.
Here is a brief set of differences that can be found in between two kinds of the experiment:
- The quasi-experiment does not imply random assignment of the participants for treatment or action.
- In a true experiment, the control of the researcher cast upon the participants is measured only by the initial terms of the treatment. In the quasi-experiment, the participants can be controlled by the things beyond the power of the researcher. The primary goal of the researcher is to minimize the effects of these factors.
- The quasi-experiment can give birth to several different hypotheses.
Now we have to consider the possible advantages and disadvantages of the quasi-experimental design. Quasi-experiments are widely spread, but cannot be applied everywhere. Here are some things to consider:
The main advantages of these types of experiment are as follows:
- This type of the experiments is widely used in various social and human sciences, where picking the equal experimental groups is always complicated enough.
- For example, you can write about the harmful effects of smoke or alcohol on unborn children. In the true experiment, you might set the participants, the pregnant women, to smoke which is absolutely unethical and illegal. In the quasi-experiment, you just need to ask pregnant women if they smoke, how much and how often and assign them to different groups.
- When the quasi-experimental design faces case studies, it can reinforce the data and information from it.
The disadvantages of such types of an experiment exist as well:
- Lack of randomization can affect the result, making them lose their meaning. That is why the quasi-experiments are considered non-scientific and irrelevant in most sciences.
- The factors that affected the participants before the experiment cannot be taken into account by the quasi-experiment design. In our example of smoking pregnant women, they can sound like: what cigarettes do they smoke, or why did they start smoking.
- Some quasi-experiments still need to control many factors. For example, if a researcher wants to compare the different sports techniques, he or she must pick the participants with equal physical talents and conditions.
Different Types of Quasi-Experimental Design and Ways of Their Applying
The types of quasi-experimental research design depend on various factors. They can include difficulty, science they are applied in, conditions, desired results, etc. In general, there are a lot of different types of quasi-experimental designs that exist and appearing from day to day. Among them, there are some traditional ones that can be recognized easily.
The nonequivalent groups design implies getting the control group that is similar to the control group that obtains the quasi-independent variable. For instance: do sports affect the long-term happiness and health? In this type of experiment, you cannot be sure that the groups were equal before the experiment.
The regression-discontinuity design (RD) is a kind of the experiment with a special way the participants are assigned to the conditions. In this case, the participants are assigned with using of a specific cutoff score. Thus we assign the experiment to people who deserve or need it.
The time series designs are aimed to measure the variables with different types of dependence on different occasions before and after the occurrence of variable independence.
Here is a brief description of these types of the design. More descriptions and examples of other quasi-experiments you can find on the Internet. Write down the key point of this article, memorize them and make your experiments actual and relevant with our help.