Experimental Design: A Background

Experimental design is now considered a standard methodology in research. However, this now classic design has not always been a standard approach. In this post, we will the following

  • The definition of experiment
  • The history of experiments
  • When to conduct experiments


The word experiment is derived from the word experience. When conducting an experiment, the researcher assigns people to have different experiences. He then determines if the experience he assigned people to had some effect on some sort of outcome. For example, if I want to know if the experience of sunlight affects the growth of plants I may develop two different experiences

  • Experience 1: Some plants receive sunlight
  • Experience 2: Some plants receive no sunlight

The outcome is the growth of the plants.By giving the plants different experiences of sunlight I can determine if sunlight influences the growth of plants.

History of Experiments

Experiments have been around informally since the 10th century with work done in the field of medicine. The use of experiments as known today began in the early 20th century in the field of psychology. By the 1920’s group comparison became an establish characteristics of experiments. By the 1930’s, random assignment was introduced. By the 1960’s various experimental designs were codified and documented. By the 1980’s there was literature coming out that addressed threats to validity.

Since the 1980’s experiments have become much more complicated with the development of more advanced statistical software problems. Despite all of the new complexity, normally simple experimental designs are easier to understand

When to Conduct Experiments

Experiments are conducted to attempt to establish a cause and effect relationship between independent and dependent variables. You try to create a controlled environment in which you provide the experience or independent variable(s) and then measure how they affect the outcome or dependent variable.

Since the setting of the experiment is controlled. You can say withou a doubt that only the experience influence the outcome. Off course, in reality, it is difficult to control all the factors in a study. The real goal is to try and limit the effect that these other factors have on the outcomes of a study.


Despite their long history, experiments are relatively new in research. This design has grown and matured over the years to become a powerful method for determining cause and effect. Therefore, researchers should e aware of this approach for use in their studies.

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