Forum:Conceptual - Do I need to justify myself if I generate more than three replicates?


I am performing an experiment with bacteria that involves 2 different conditions and I am trying to see if there is a statistically significant difference between the two. Now I think there is a good amount of stochasticity in the experiment that can affect the results in a major way. So, I personally don't feel confident with just three replicates, since even one replicate with way-off outcomes (probably due to the stochasticity) can affect the conclusions a lot. So, I thought of doing 5 replicates for this study. I have not performed power analysis to come up with this number, but I just feel a bit more confident with n=5 than n=3 in this situation.

My question is, do I need to justify why I am working with 5 replicates rather than 3 (which seems to be the standard in biology)? Three replicates is the minimum number you need to calculate variance at all - I am not sure how one can be confident with just 3, especially when there is a lot of variability in the data. But still, just like 3 is an arbitrary number for replicates, would anyone object if it is 5?

Any suggestion/input would be appreciated.

PS - every replicate involves taking a sample from the same bacterial freezer stock, which was generated from a single colony of that bacteria. In other words, I don't think these are biological replicates but technical.




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