An experimental investigation is unique in that it involves the deliberate or purposeful manipulation of a ‘variable’ (or variables) and the observation of the effects of that manipulation. In an experimental investigation, your teacher will likely ask you to identify things such as an independent (or manipulated) variable, a dependent (or responding) variable, and controlling variables (or constants). Your teacher will also likely ask you to write a hypothesis proposing a logical relationship between the variables before performing your experiment, as well as make hypothesis-based predictions for each of the planned trials of the experiment.
In this way, experimental research is similar to comparative research, which also aims to alter–or manipulate–some aspect of the conditions in which the objects, events, or systems occur, unfold, or reside. Unlike in comparative research, however, in experimental research the scientist subjects the objects or events to a predetermined (or deliberate) experimental treatment. In other words, the objects or events under consideration are not allowed to exist each in somewhat ‘natural’ settings and/or in relatively ‘typical’ situations…they are deliberately manipulated by the scientist (or scientists).
Experiments are used across all scientific disciplines–as well as some social science disciplines–to investigate all kinds of questions. In some cases, scientific experiments are used for exploratory purposes in which the scientist does not know what the dependent (or responding) variable is. In this type of experiment, the scientist will manipulate an independent (or manipulated) variable and observe what the effect of the manipulation is in order to identify a dependent/responding variable (or variables). Scientific experiments are also commonly used to quantify the magnitude of a relationship between two or more variables.
Like both descriptive and comparative investigations, experimental investigations typically involve the systematic observation and detailed descriptions of objects, organisms, populations, instances, situations, or phenomena in such a way that the experiment could be replicated by other scientists. To be systematic means that experimental investigations must be characterized by both rigor and consistency. Your science teacher will talk with you in more detail about these two important terms–rigor and consistency–during your experimental investigations.
To learn more about experimental research, you can visit the excellent Visionlearning site, but if you’d rather begin trying to master some of the key skills and sensibilities needed to do experimental research well, then proceed directly to the exercises.
Last updated: July 2019