My experiment gives data of 12 biological replicates. This would be sufficient to calculate the mean and give a valid standard deviation. However, there might have been some pipetting errors that affect all replicates. So I repeat the experiment from scratch 3 times. Now I have 3x 12 samples. How do I represent the data? Take the mean of the 3 means and the standard deviation of the 3 means?
EDIT: more info;
I am comparing protein expression between constructs transformed into the cells. Thus I have like 10 x 12 biological replicates (10 means that I compare). This whole thing I repeat 2 times. Should I pool the data if I see that they are all really similar?