Determining the VARIABLES

jesika917 · Post by **jesika917** » Tue Mar 27, 2007 9:34 pm

I'm doing an experiment testing for the lead concentration in soil in different locations.

So far, I understand that the concentration of lead would be my dependent variable.

The soil samples would be the independent variable.(?)

What would be my control variable?

Craig_Bridge · Post by **Craig_Bridge** » Wed Mar 28, 2007 5:31 am

What grade are you in? Working with lead and lead assays may or may not be appropriate for your grade level. Additionally, you should ask the Science Fair sponsoring authority if this falls under a hazardous materials situation. You maybe able to do the experiment but not display any of the materials at the fair or you may not be allowed to enter it period. If you are allowed to do the experiment, you are going to need somebody to supervise your handling and disposal of the materials.

Controlled Variables are things that you need to control in order to prove or disprove your hypothesis. What is your hypothesis?

What assay methodology are you using? Different assay methods or measurement techniques can be affected by different things. In order for the assay to measure what you intend, you have to control everything that might affect the measurement that does not involve your dependent variable.

BTW: Control has another common meaning in this kind of experiment. With many assay methods you have to run "controls". In other words, you have to assay one or more controls or known samples to validate the assay methodology.