by Disinvestment Supporter

Created on: January 21, 2011

Variables are central to any scientific endeavor, because they represent the action of an experiment or observation. In an experiment, we refer to them as dependent, independent, and extraneous, concepts that are learned best through examples.

The independent variable should be prominently displayed in a science fair project that follows the experimental method. Independent simply means that the variable is only being manipulated by the researcher. Imagine an experiment where you want to find out whether giving homework really helps improve students' math grades. Or maybe you want to find out the highest volume you can turn your stereo before your parents make you turn it down. The amount of homework we give, or the volume of the stereo, is the independent variable.

Dependent variables that are measured should be displayed, as well as a few extraneous variables that are being controlled for. Dependent means that the researcher expects it to change, or not, in response to the independent variable. A parent might be curious to know whether the volume level of their child's music is a product of their emotional state, or a principal might question whether new math teachers tend to give more or less homework than more experienced ones, In these cases the stereo volume and amount of homework given have become dependent variables. Can you name the new independent variables? Can you name the dependent variables in the preceding paragraph?

The relationship of variables, or things that change, to each other will depend on the hypothesis. The hypothesis often begins as a research question, either practical or based in theory, though it will need to be stated as a prediction if an experiment is intended, and not simply a case study or observation. In an experiment, there are often extraneous variables. These are defined as variables that potentially influence the dependent variable. We have to control for these, or minimize their influence, to make sure that we are truly testing for our independent variable.

Imagine you find that turning the stereo volume to four does not get a reaction yet turning it to five gets a request to turn it down. That was on Monday. On Tuesday you decide to run the experiment again and find you can turn the stereo up to 8. Obviously there are extraneous variables influencing whether your parents consider the music to be too loud. Maybe they were stressed out on Monday and had a lower tolerance for loud music, or maybe they actually like the

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