You are testing the injection of a new chemical on mice to see if it can shrink tumors. To properly administer the chemical, it must be dissolved in water with ascorbic acid (vitamin C) and injected into the middle of a tumor. As a positive control, you plan to similarly prepare and inject a chemical that is already known to shrink tumors. What is the best choice for a negative control treatment?
Would it be injection of water and ascorbic acid? A negative control is when you want nothing to happen right? Or would it be injection of nothing?
The best choice for a negative control treatment would depend on the specific experiment and what you are trying to assess. In this case, a negative control would be a treatment that does not have any effect on tumor growth or shrinkage.
If you are specifically testing the effect of the chemical when dissolved in water with ascorbic acid, then injecting just water and ascorbic acid (without the new chemical) would be an appropriate negative control. This would allow you to evaluate whether it is the combination of the chemical and ascorbic acid or some other factor that is responsible for any observed tumor shrinkage.
On the other hand, if you are specifically testing the injection procedure's effect on tumor growth, then the negative control could involve injecting nothing at all. This would help you determine whether the injection procedure itself influences tumor shrinkage independently of any chemical or substance.
It's essential to consider the goals of your experiment and choose a negative control that allows you to isolate and evaluate the specific factors you are testing.