What is a co-variable in an investigation?

Question

I'm not quite sure. I know you have them in a correlational experiment, but i'm not entirely sure what they are. Could you please say what they are, and then give an example?

Thanks.

Answer 1

To me, they are aspects of an investigation which are equally important and/or relevant to the discernment of a solution.

For example, time and money spent could be co-variables in an economic investigation.