Experimental Design

Member of group 5 :

1. Zenna Oktania R. (20181111040)

2. Richard Himawan (20181111048)

3. Sobariyah Juheng (20181111067)

What is experimental design?

Experimental design means creating a set of procedures to test a hypothesis. The experimental research method is a quantitative research method used to determine the effect of the independent variable (treatment) on the dependent variable (result) under controlled conditions. Conditions are controlled so that no other variable (other than the treatment variable) affects the dependent variable. In order for conditions to be controlled, in experimental research using a control group and often experimental research is carried out in the laboratory.

Types of designs in experimental research methods

There are several forms of experimental design that can be used in research for theses, theses and dissertations, namely: Pre-Experimental Design, True Experimental Design, Factorial Design, and Quasi Experimental Design.

1. Pre-Experimental Design (Nondesigns)

It is called the Pre Experimental Design because this design does not include a serious experiment, because there are still external variables that also influence the formation of the dependent variable. So the experiment which is the dependent variable is not solely influenced by the independent variable. This can occur in the absence of control variables, and the sample is not randomly selected. There are several forms of pre-experimental designs, namely One-Shot Case Study, One-Group Pretest-Posttest Design, and Intact-Group Comparison.

2. True Experimental Design

In this study, the researcher can control all external variables that affect the course of the experiment. That way the quality of the implementation of the research design (internal validity) can be high. The main characteristic of true experimental design is that the sample used for both the experimental and control groups is taken randomly from a certain population. So, true experimental design is a control group and a randomly selected research sample. There are two forms of true experimental design, namely Posttest Only Control Design and Pretest Group Design.

3. Factorial Design

Factorial design is a modified form of true experimental design. The modification made is by observing the possibility of a moderating variable affecting the independent variable (treatment) on the dependent variable (outcome).

4. Quasi Experimental Design

Quasi Experimental Design is also a development of true experimental design, but this design tends to be difficult to implement. This design has a control group, but it cannot fully function to control external variables that affect the implementation of the experiment / experiment. However, this design is better than pre-experimental design. Quasi experimental design is used because in practice it is difficult to obtain a control group that can be used for research.

In an administrative or management activity, it is often impossible to use some of its employees for experiments and some of it is not. Therefore, a quasi experimental design was developed to overcome the difficulties in determining the control group in the study. There are two forms of quasi-experimental design, namely Times-Series Design and Nonequivalent Control Group Design.

How to use experimental Research Design?

The 4 steps of using the experimental research design are:

Step 1: Define your research question and variables

You should begin with a specific research question in mind. You may need to spend time reading about your field of study to identify knowledge gaps and to find questions that interest you. To translate your research question into an experimental hypothesis, you need to define the main variables and make predictions about how they are related. Start by simply listing the independent and dependent variables.

Then you need to think about possible extraneous and confounding variables and consider how you might control them in your experiment. Finally, put these variables together into a diagram. Use arrows to show the possible relationships between variables and include signs to show the expected direction of the relationships.

Step 2: Write your hypothesis

Now that you have a strong conceptual understanding of the system you are studying, you should be able to write a specific, testable hypothesis that addresses your research question. The next steps will describe how to design a controlled experiment. In a controlled experiment, you must be able to:

• Systematically and precisely manipulate the independent variable(s).

• Precisely measure the dependent variable(s).

• Control any potential confounding variables.

If your study system doesn’t match these criteria, there are other types of research you can use to answer your research question.

Step 3: Design your experimental treatments

How you manipulate the independent variable can affect the experiment’s external validity – that is, the extent to which the results can be generalized and applied to the broader world.

First, you may need to decide how widely to vary your independent variable. Second, you may need to choose how finely to vary your independent variable. Sometimes this choice is made for you by your experimental system, but often you will need to decide, and this will affect how much you can infer from your results.

Step 4: Assign your subjects to treatment groups

How you apply your experimental treatments to your test subjects is crucial for obtaining valid and reliable results.

First, you need to consider the study size: how many individuals will be included in the experiment? In general, the more subjects you include, the greater your experiment’s statistical power, which determines how much confidence you can have in your results. Then you need to randomly assign your subjects to treatment groups. Each group receives a different level of the treatment (e.g. no phone use, low phone use, high phone use). You should also include a control group, which receives no treatment. The control group tells us what would have happened to your test subjects without any experimental intervention. When assigning your subjects to groups, there are two main choices you need to make:

1. A completely randomized design vs a randomized block design.

Randomization is an experiment can be completely randomized or randomized within blocks (aka strata):

• In a completely randomized design, every subject is assigned to a treatment group at random.

• In a randomized block design (aka stratified random design), subjects are first grouped according to a characteristic they share, and then randomly assigned to treatments within those groups. Sometimes randomization isn’t practical or ethical, so researchers create partially-random or even non-random designs. An experimental design where treatments aren’t randomly assigned is called a quasi-experimental design.

2. A between-subjects design vs a within-subjects design.

In a between-subjects design (also known as an independent measures design or classic ANOVA design), individuals receive only one of the possible levels of an experimental treatment

• In medical or social research, you might also use matched pairs within your between-subjects design to make sure that each treatment group contains the same variety of test subjects in the same proportions.

• In a within-subjects design (also known as a repeated measures design), every individual receives each of the experimental treatments consecutively, and their responses to each treatment are measured.

Within-subjects or repeated measures can also refer to an experimental design where an effect emerges over time, and individual responses are measured over time in order to measure this effect as it emerges.

Counterbalancing (randomizing or reversing the order of treatments among subjects) is often used in within-subjects designs to ensure that the order of treatment application doesn’t influence the results of the experiment.

Examples of Experimental Research

Experimental research examples are different, depending on the type of experimental research design that is being considered. The most basic example of experimental research is laboratory experiments, which may differ in nature depending on the subject of research.

1. Administering Exams After The End of Semester

During the semester, students in a class are lectured on particular courses and an exam is administered at the end of the semester. In this case, the students are the subjects or dependent variables while the lectures are the independent variables treated on the subjects.

Only one group of carefully selected subjects are considered in this research, making it a pre-experimental research design example. We will also notice that tests are only carried out at the end of the semester, and not at the beginning.

Further making it easy for us to conclude that it is a one-shot case study research.

2. Employee Skill Evaluation

Before employing a job seeker, organizations conduct tests that are used to screen out less qualified candidates from the pool of qualified applicants. This way, organizations can determine an employee's skill set at the point of employment.

In the course of employment, organizations also carry out employee training to improve employee productivity and generally grow the organization. Further evaluation is carried out at the end of each training to test the impact of the training on employee skills, and test for improvement.

Here, the subject is the employee, while the treatment is the training conducted. This is a pretest-posttest control group experimental research example.

3. Evaluation of Teaching Method

Let us consider an academic institution that wants to evaluate the teaching method of 2 teachers to determine which is best. Imagine a case whereby the students assigned to each teacher is carefully selected probably due to personal request by parents or due to stubbornness and smartness.

This is a no equivalent group design example because the samples are not equal. By evaluating the effectiveness of each teacher's teaching method this way, we may conclude after a post-test has been carried out.

However, this may be influenced by factors like the natural sweetness of a student. For example, a very smart student will grab more easily than his or her peers irrespective of the method of teaching.

Why Use Experimental Research Design?

Experimental research design can be majorly used in physical sciences, social sciences, education, and psychology. It is used to make predictions and draw conclusions on a subject matter.

Some uses of experimental research design are highlighted below.

Medicine: Experimental research is used to provide the proper treatment for diseases. In most cases, rather than directly using patients as the research subject, researchers take a sample of the bacteria from the patient's body and are treated with the developed antibacterial

The changes observed during this period are recorded and evaluated to determine its effectiveness. This process can be carried out using different experimental research methods.

Education: Asides from science subjects like Chemistry and Physics which involves teaching students how to perform experimental research, it can also be used in improving the standard of an academic institution. This includes testing students' knowledge on different topics, coming up with better teaching methods, and the implementation of other programs that will aid student learning.

Human Behavior: Social scientists are the ones who mostly use experimental research to test human behavior. For example, consider 2 people randomly chosen to be the subject of the social interaction research where one person is placed in a room without human interaction for 1 year.

The other person is placed in a room with a few other people, enjoying human interaction. There will be a difference in their behavior at the end of the experiment.

UI/UX: During the product development phase, one of the major aims of the product team is to create a great user experience with the product. Therefore, before launching the final product design, potential are brought in to interact with the product.

For example, when finding it difficult to choose how to position a button or feature on the app interface, a random sample of product testers are allowed to test the 2 samples and how the button positioning influences the user interaction is recorded.

What are the Data Collection Methods in Experimental Research?

Data collection methods in experimental research are the different ways in which data can be collected for experimental research. They are used in different cases, depending on the type of research being carried out.

Observational Study: This type of study is carried out over a long period. It measures and observes the variables of interest without changing existing conditions.

When researching the effect of social interaction on human behavior, the subjects who are placed in 2 different environments are observed throughout the research. No matter the kind of absurd behavior that is exhibited by the subject during this period, it's condition will not be changed.

This may be a very risky thing to do in medical cases because it may lead to death or worse medical conditions.

Simulations: This procedure uses a mathematical, physical, or computer models to replicate a real-life process or situation. It is frequently used when the actual situation is too expensive, dangerous, or impractical to replicate in real life.

This method is commonly used in engineering and operational research for learning purposes and sometimes as a tool to estimate possible outcomes of real research. Some common situation software are Simulink, MATLAB, and Simul8.

Not all kinds of experimental research can be carried out using simulation as a data collection tool. It is very impractical for a lot of laboratory-based research that involves chemical processes.

Surveys: A survey is a tool used to gather relevant data about the characteristics of a population, and is one of the most common data collection tools. A survey consists of a group of questions prepared by the researcher, to be answered by the research subject.

Surveys can be shared with the respondents both physically and electronically. When collecting data through surveys, the kind of data collected depends on the respondent, and researchers have limited control over it.

Formplus is the best tool for collecting experimental data using surveys. It has relevant features that will aid the data collection process and can also be used in other aspects of experimental research.

Conclusion

Experimental research designs are often considered to be the standard in research designs. This is partly due to the common misconception that research is equivalent to scientific experiments—a component of experimental research design.

In this research design, one or more subjects or dependent variables are randomly assigned to different treatments (i.e. independent variables manipulated by the researcher) and the results are observed to conclude. One of the uniqueness of experimental research is in its ability to control the effect of extraneous variables.

Experimental research is suitable for research whose goal is to examine cause-effect relationships, e.g. explanatory research. It can be conducted in the laboratory or field settings, depending on the aim of the research that is being carried out.

Please kindly check the following files:

Experimental Design+.docx

Download DOCX • 23KB

Experimental Design.pptx

Download PPTX • 4.55MB