To investigate how the phylogenetic ordering of mutations influences the amplification pattern we see across our simulations in Section 3.3.2, we chose to introduce the EGFR and PDGFRA amplified sub-populations at various introduction times, tE* and tP* determined by the size, NE or NP, of the growing tumour, which we also include in the sensitivity analysis with minimum and maximum values of 3NI and 9NI, where NI is size of the initial population of non-amplified tumour cells. The gene discussed is PDGFRA; the disease is neoplasm.