A friend of mine is trying to "be sure" that her counting method for phytoplankton communities is solid and unbiassed. She makes 3 essays (repeating 3 times the counting of N species of the same sample -and transforming to percentage data-) and wants to be sure that there are not significant differences between the essays, so that the method is consistent and results (in terms of percentage abundance of the N species) are homogeneous.

Which would be the propper test/s to perform in this case?

Thank you very much,

Andrés