Hi everyone,

I have been doing a biological experiment on three different days and I get this type of results:

Day 1:
Condition A: 2
Condition B: 4
Fold change: 2

Day 2:
Condition A: 2
Condition B: 4
Fold change: 2

Day 3:
Condition A: 4
Condition B: 8
Fold change: 2

As you can see, I observe a 2-fold change every time I do the experiment, which tells me there is a difference. However, my biological system present day-to-day variation (common for biological systems).

If I do a simple T test comparing:
Sample A: 2, 2, 4
Sample B: 4, 4, 8
Then I don't get a significant difference.

If I normalize everything to the control (sample A) on that day, I'll get:
Sample A: 1, 1, 1
Sample B: 2, 2, 2
Then I get a crazy P value, but I also feel I am doing something wrong (?)

What is the best way to proceed and what is the best statistical test?

Thank you!
Alexis