As part of my PhD work, I've conducted an inoculation experiment concerned with marine phytoplankton community productivity (dependent variable, as 'no. of cells') vs nutrient availability. I have two factors:
- Nutrient Treatment (4 levels - including control)
- Time (sampled at 5 points)
The puzzling aspect to this design is that within the phytoplankton community, there are 4 main taxonomic groups (each with 'no. of cell' data), which I need to account for (i.e. I would like to know which of these groups significantly differed both within and between treatments over the entire sampling regime).
So, I understand a post-hoc test (e.g. TukeyHSD) will be needed to run multiple comparisons test in order to elucidate group differences, but first need to know which test to initially run (i.e. Two-way repeated measures ANOVA, or multiple ANOVA), and in what structure? Or, is it simply not possible to simultaneously analyse for between phytoplankton group differences?