Experimental research refers to experiments conducted in laboratories or observations under controlled conditions. Researchers aim to find the cause-and-effect relationship between two or more variables.
Participants in the experiment are selected and observed.
They receive treatments such as changes in room temperature, diet, atmosphere, or new drugs to study the outcomes. Experiments can vary from personal and informal natural comparisons.
How to Conduct Experimental Research?
The following are the key steps involved in conducting experimental research.
Step 1. Identify and Define the Problem
You need to identify a problem in your field of study and describe your research question.
- Example 1: You want to know about the effects of social media on the behavior of youngsters. It would help if you found out how much time students spend on the internet daily.
- Example 2: You want to find out the adverse effects of junk food on human health. It would help if you found out how frequent consumption can affect an individual’s health.
Step 2. Determine the Number of Variables
You need to determine the number of variables. The independent variable is the predictor and is manipulated by the researcher.
At the same time, the dependent variable is the result of the independent variable.
| Independent Variable (IV) | Dependent Variable (DV) | Confounding Variable (Potential) |
|---|---|---|
| The number of hours of sleep per night (Manipulated or Observed) | Student performance on a morning exam (Measured outcome) | Study time/preparation for the exam. Students who sleep less might also study less, making it difficult to determine if the lower score is due to lack of sleep or lack of study. |
| Type of fertilizer used on tomato plants (e.g., Organic vs. Chemical) (Manipulated) | Final weight of the harvested tomatoes (Measured outcome) | Amount of sunlight/water received. If the Organic group is placed in a sunnier spot, the difference in weight may be due to the sun, not the fertilizer. |
| Participation in a stress-reduction workshop (Yes/No) (Manipulated) | Self-reported anxiety levels after one month (Measured outcome) | Prior baseline anxiety levels or major life events during the study period. A traumatic event during the month could increase anxiety regardless of the workshop. |
Predictions:
- In the first example, we predicted that increased social media usage negatively correlates with youngsters’ negative behaviour.
- In the second example, we predicted the positive correlation between a balanced diet and a good, healthy and a negative relationship between junk food consumption and multiple health issues.
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Step 3. Formulate the Hypothesis
One of the essential aspects of experimental research is formulating a hypothesis.
A researcher studies the cause and effect between the independent and dependent variables and eliminates the confounding variables.
| Threat | Definition | Example |
|---|---|---|
| Reactive/interactive effects of testing | A null hypothesis is when there is no significant relationship between the dependent variable and the independent variable. | The usage of social media does not correlate with the negative behaviour of youngsters. |
| Selection of participants | The alternative hypothesis is the theory that a researcher seeks to prove, and there is a significant relationship. | Overuse of social media affects the behaviour of youngsters adversely. |
Step 4. Selection and Assignment of Subjects
It’s an essential feature that differentiates the experimental design from other research designs.
You need to select the number of participants based on the requirements of your experiment. Then the participants are assigned to the treatment group.
There should be a control group without any treatment to study the outcomes without applying any changes compared to the experimental group.
| Randomization (Random Assignment) | Stratified Sampling (Random Selection) |
|---|---|
| Definition: The process of assigning already-selected participants to the treatment or control groups in an experiment entirely by chance. | Definition: A probability sampling technique where the population is first divided into homogeneous subgroups (strata), and then a simple random sample is taken from each stratum. |
| Purpose: To ensure that the groups are equivalent at the start of the experiment, minimizing the threat of selection bias and maximizing internal validity. | Purpose: To ensure that specific subgroups are adequately represented in the sample, which increases the external validity and precision of estimates for the population. |
| Example: The participants who have already been selected for a study are randomly assigned by a coin flip or random number generator to either the new Drug Group or the Placebo Group. | Example: A population of university students is divided into strata based on class year (Freshman, Sophomore, Junior, Senior). A proportional number of students is then randomly selected from each of these four strata. |
Matching:
Even though participants are selected randomly, they can be assigned to the various comparison groups. Another procedure for selecting the participants is ‘matching.’
The participants are selected from the control group to match the experimental group’s participants in all aspects based on the dependent variables.
Step 5. Select a Research Design
You need to select a research design according to the requirements of your experiment. There are many types of experimental designs as follows.
| Type of Research Design (Experimental) | Definition and Key Feature |
|---|---|
| Two-Group Post-test Only | Compares an experimental group that receives the treatment to a control group that does not. The dependent variable is measured only once after the treatment for both groups. Requires random assignment. |
| Two-Group Pre-test Post-test | Measures the dependent variable before (pre-test) and after (post-test) treatment for both a randomly assigned experimental group and a control group. Allows measurement of change over time. |
| Solomon Four-Group Design | Combines the two designs above: it uses four randomly assigned groups. Two groups receive a pre-test (one treatment, one control) and two groups do not (one treatment, one control). The primary advantage is controlling for the testing threat to external validity. |
| Factorial Design | A design that involves two or more independent variables (called factors), each having two or more levels. It allows researchers to study the main effects of each factor and their interaction effects. |
| Randomized Block Design (RBD) | Used when there is a known extraneous variable (the block) that might influence the results. Participants are first grouped into homogeneous blocks based on this variable, and then participants within each block are randomly assigned to treatment groups. Reduces error variance. |
| Cross-Over Design | A type of repeated measures design where subjects receive a sequence of different treatments over different time periods, often with a washout period between treatments. The order of treatments is typically randomized. |
| Repeated Measures Design | An experimental design where the same participants are exposed to all levels of the independent variable. Participants serve as their own control, reducing error and requiring fewer subjects than independent group designs. |
Step 6. Meet Ethical and Legal Requirements
- Participants of the research should not be harmed.
- The dignity and confidentiality of the research should be maintained.
- The consent of the participants should be taken before experimenting.
- The privacy of the participants should be ensured.
- Research data should remain confidential.
- The anonymity of the participants should be ensured.
- The rules and objectives of the experiments should be followed strictly.
- The privacy of the participants should be ensured.
Tips for Ethical Considerations:
- Right to withdraw
- Provide full information about the experiment.
- Avoid offensive language in questions.
- Acknowledge all sources (APA/MLA/Harvard)
Step 7. Collect and Analyse Data and Formulate the Conclusion
Collect the data by using suitable data collection methods according to your experiment’s requirements, such as observations, case studies, surveys, interviews, questionnaires, etc. Analyse the obtained information.
Write the report of your research. Present, conclude, and explain the outcomes of your study.
Frequently Asked Questions
In experimental research, challenges like ethical concerns, participants’ bias, or limited external validity can occur.
To control the variables in experimental research, we use techniques like randomisation, matching, and control groups to minimise outside influence.
Yes, experimental research can be applied outside the laboratory in real-world settings through field experiments and natural experiments.
