If you're using the FFXIV-APP parser, ALL DoTs are being calculated wrong. It uses the initial hit's damage as it's per-tick damage as well. This goes for any class that has a damage over time ability. Example: My Thunder III hits for 118 on its initial hit, but does about 72 dmg/tick avg. (+/- 5%). The parser increased my damage by 118 per tick instead of its actual damage. Phlebotomize does this as well. This behaviour leads to very erratic parsing of DoTs in the app. For Miasma, it increases the damage by the "DoT Average" per tick, regardless of a crit or not. Technically in this case, the parser is UNDERrepresenting Miasma's damage, not inflating it. Bio does the same thing. This often under-represents the damage. Needless to say the parser handles DoT abilities in a very incorrect manner.

Note: This is as of the latest update on 9/21.