if you use 2 graphs on same page, it more like u sustract one from another and get absolute gain. When you divide you tell it is "relative" gain.
Hope it helps
you draw support and resistance lines for the ratio
can you do this?
too many things that can affect the ratio. each of the IHI stocks can affect it, DXCM price can affect it
so than you chart shows 200% what does it mean ? does it mean that DXCM is 200% ahead of IHI?