Standard deviation question

tnad

New Member
#1
Hello,

I have 3 replicates from an experiment and i would like to calculate their standard deviation; however, each of the replicates is itself an average of 3 other replicates and has its own standard deviation value. How do you go about calculating this total standard deviation. Do you simply covert them into 9 replicates and get that standard deviation? It doesnt seem right to lump them up since the errors could be of a different nature.
 
#2
I think you should read about the difference between Replication vs Repetition.

You have three replicates and tree repetitions inside a replicate.
If you assume your repetitions as replicates, you are pseudoreplicating.

I suggest to read papers related with this topic e.g http://www.jstor.org/pss/2265754

Regards