18 March 2010

Dear webmaster,

I’m having a problem with experimental design. I'm not sure how to make the data into a bar-graph and I'm not sure how to label the independent, dependent, and control variables.

This is the point of my experiment. I'm adding glucose to yeast to produce alcohol. My glucose solution concentrations are 10, 20, 30, 40%. I am looking for the amount of alcohol produced for any instance and have to graph the results.

Dear reader,

The glucose solution concentration rate is the independent variable since it’s not dependent on any factor besides your decision and is located on the horizontal axis of your graph.

The amount of alcohol produced is the dependent variable since it’s dependent on the independent variable (glucose solution concentration), and is located on the vertical axis of your graph.

In other words, the dependent variable is the outcome of the experiment and is triggered by the independent variable.

A control variable is a variable that is held constant in order to analyze the relationship between other variables without interference. For example, you must keep the same temperature and light radiation level in all your Petri dishes with the different concentrations of glucose in order to prevent distortion of you results.