Principles of experimental design in research

(1). Randomization

The principle of randomization involves the allocation of treatment to experimental units at random to avoid any bias in the experiment resulting from the influence of some unknown factor that may affect the experiment. In the development of analysis of variance, errors are assumed to be random and independent. In turn, the observations also become random.

(2). Replication

In the replication principle, any treatment is repeated several times to obtain a valid and more reliable estimate which is impossible to obtain with one observation only. This principle provides an efficient way of increasing the precision of an experiment. The accuracy increases with the increase in the number of observations. Replication provides more observations when the same treatment is used, so it increases precision.

(3). Local control

The local control principle involves regulating all factors except the ones under investigation. The replication is used with local control to reduce the experimental error. For example, if the experimental units are divided into different groups such that they are homogeneous within the blocks, then the variation among the blocks is eliminated and ideally, the error component will contain the variation due to the treatments only. This will, in turn, increase the efficiency.

(4). Manipulation of Variables

Manipulation of variables involves altering the independent factors in the experimental research design. This allows the researcher to establish the causal relationship between the treatment and dependent variables in the study. It determines whether the independent variable causes a significant change to the dependent factor.

The Experimental Design Process

An experimental design is the systematic plan for assigning research units to certain treatments and the analysis of the results. For an exceptional experiment, the researcher must follow these steps:

Step 1: State the research question

Formulating the research question directs the course of the study to be conducted. When stating the study inquiry, devise a relevant issue impacting the community or society and record the observations, conduct rigorous research and summarize current understandings about the topic, and state a sentence highlighting the focus of the study in the form of a question. It should be specific and measurable.

Step 2: State hypothesis

The hypothesis is a proposed explanation of the outcome of the experiment. It guides the course of the research and all experimental findings are viewed through the lens of the stated prediction. In this step, write a statement that predicts the outcome of the study and identify the independent and dependent variables that will be used in the research.

Step 3: Design the experiment

When designing the experiment, highlight specific details of the experimental procedure. In this step: 1.) Identify and list all materials to be used in the study and safety precautions 2.) Illustrate numerically the number of steps to be followed when testing the hypothesis 3.) Identify the control variables 4.) demonstrate the process of data collection and recording 5.) design a data table to record information 6.) Plan an effective strategy to summarize data. A well-designed experiment addresses the predictions stated in the hypothesis.

Step 4: Conduct the experiment

When experimenting, the researcher follows the steps outlined in the design. This step involves collecting data and filling the data table with units from the procedure, identifying any sources of statistical errors, and making notes of future research ideas in the field.

Step 5: Analyze the Data

Analyzing the data involves the application of statistical analysis methods depending on the type of data collected. After conducting the analysis, synthesize and present the data using graphs and charts while observing patterns and trends. In narrative form, clearly illustrate all analyses including calculations, and draw conclusions based on the data while reflecting on the stated hypothesis.

Step 6: Communicate Findings

The aim of communicating findings is to increase the knowledge base that future studies will be built around. State the conclusions made from the study, illustrate the rationale of the research, and explain the next steps after completion. The succeeding steps can be: changing the hypothesis, redesigning the study, coming up with research questions based on the conducted research, or proceeding to a new/related area of inquiry.

Experimental Design Diagram

The experimental design diagram illustrates the essential components of an experiment. It typically consists of: