Science Buddies: "Ask an Expert"

I was wondering if anybody knows the answer to this question. We are doing the experiment on how are antibodies used for blood typing. I know that my controlled variables are the antiserums, amount of drops, and the amount of time to mix the solution. So, in this experiment I don't necessarily have a controlled group because the things that I'm not changing are the antiserums, drops, and time. The only different thing is the blood samples that are from different donors. Is this correct? Please, correct me if I'm wrong.

Hi!
The objective of this experiment is to determine the blood type of each sample, so you are correct in the assumption that each blood sample comes from a different "donor." Control groups are used in experiments in which one variable is being altered. As this experiment is observational, and no variables are being manipulated, a control group is not necessary. Hopefully this helps, and let us know if you have any other questions!
Good luck with your experiment,
Chloe

Hello,

Very interesting experiment, keep us informed of developments and results.