5 Protocol 3 - Geochemical and petrographic data

The following example applies protocol 3 to confirm workshops’ provenance groups.

Protocol 3 consist in:

1. Select geochemical compositional data (CoDa) and ordinal petrographic data;
2. Centred log-ratio transformation (clr) and transform to ranks;
3. Extended Gower distance, using Relative ranking difference (RRD);
4. Apply Principal Coordinates Analysis (PCoA);
5. Perform PERMANOVA & PERMDISP tests;

Last, search for outliers and re-do protocol excluding outliers.

NOTE: The initial procedures must be ran at least once before any protocol can be applied.

See protocol 2, for consulting references on the extended Gower distance.