Please find enclosed the script and an example dataset, which will illustrate how to organize the data.
You need to subset the dataset by medium, which will give you four datasets, one for each medium.
Select as grouping column either 'type' or 'batch':
- With 'type' a comparison is made between all 3 reference batches (merged) versus all 3 test batches (merged)
- With 'batch' a comparison is made between a single reference and a single test batch.
Piet