How is mission rank/MP determined, while joining mid-mission?

[MegaZoneXE]

Well we all know there is no possible way to get a S rank( highest rank joining mid-mission is A rank) or getting the highest amount of mission point (MP) when joining a party mid-mission.

i always thought it was either how many monsters you killed during the time you joined(mid-mission) intil the mission is over....OR how long (duration in minutues) you were in the party intil the mission is over.

[unicorn]

I thought you can still get an S-rank if you join within the first minute. o_o; Unless I'm mistaken...

[Dhylec]

I thought you can still get an S-rank if you join within the first minute. o_o; Unless I'm mistaken...
I think ya mean A rank within 1st min. I only got S if I joined before missions really starts.