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Hello Dakka!

I'm thinking about outfitting my IG CCS with some plasma weapons at the moment. I was a bit concerned with gets hot! wounds killing all my expensive veterans, so I did some mathhammer.

I assumed that, at best, a plasma gun will shoot three times at rapid-fire range per game. (I mount them in chimeras that will be driving here and there all the time, so I think three times 12" range is quite reasonable.)

Now, I have to admit that I used the very simple approach to calculate the risk...

1/6 chance of gets hot! * 2/3 chance of failed armor saves * 6 shots...whoa, a chance of 2/3 of blowing himself up!

Well, this is, of course, not proper stochastics. So, having had some time in the last few hours, I refreshed my mind on stochastics. The formula for binomial distribution seemed the right approach, so I calculated with

P(k) = (n k) * p^k * (1-p)^(n-k), with k as 1, 2 and 3 unsaved wounds, n=6 (shots) and p=1/9 (1/6 gets hot * 2/3 failed save).

As a result, I got...

chance of plasma gunner suffering one wound: 37.00%
chance of plasma gunner suffering two wounds: 11.56%
chance of plasma gunner suffering three wounds: 1.93%
After three wounds, the chances get very low. So, as a result, is it correct that the plasma gunner has a chance of roughly 50.5% of blowing himself up over six shots? This includes, of course, the possibility of this happening on the first shot in the game, but is this basically right math?

50% seem better than 66%, but it's still somewhat evil to let a guardsman carry that damned thing...if I'm right.

well my guardsmen have a bad habit of frying themselves the first time i shoot with the damned squad so i started putting a medic in the CCS and it worked well for me. i really only need them to shoot 1 or 2 turns, once they unload all that plasma they tend to become high priority for my opponent.

1/6 chance of gets hot! * 2/3 chance of failed armor saves * 6 shots...whoa, a chance of 2/3 of blowing himself up!

That's improper math.

You have to go the other route:

The probability to survive overheating after 1 shot:
p = 5/6 chance to survive + (1/6 to make armor save * 1/3 chance to save) = 5/6 + 1/18 = 16/18 = 8/9.
This coincides with the above.

The probability to survive overheating after 6 shots:
q = p^6 = 0.49.

with all that armour available to IG just drill the enemy before it gets within 24"

So the probability to overheat is about 0.51.
Thus you would loose one half of your plasma guys.

So, we basically have the same result, haven't we, wuestenfux

FYI, I changed the plasma gun in my command squad to some minor upgrades for other units. Yes, it's effective, but I have a problem with killing my own guys.

Hey! don't knock the IG suicide squad!

Vets with plazma and a democharge can kill alot of stuff, INCLUDING THEMSELVES!

Witzkatz wrote:So, we basically have the same result, haven't we, wuestenfux

After all, we have the same result but your math is not convincing me.

Well, you chose the route of determining the chance of survival, while I took the route of determining the chance of death. In the end, it seems to work both ways.