<![CDATA[Latest posts for the thread "Re-rolling 1's and statistics"]]> http://www.dakkadakka.com/dakkaforum/posts/list/69.page JForum - http://www.jforum.net Re-rolling 1's and statistics http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435931.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435931.page GMT Re-rolling 1's and statistics Hitting on 5s: 2/6 -> 7/18 increase of 7/6
Hitting on 4s: 3/6 -> 7/12 increase of 7/6
Hitting on 3s: 4/6 -> 7/9 increase of 7/6
Hitting on 2s: 5/6 -> 35/36 increase of 7/6

Yes, the maths checks out.]]> http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435950.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435950.page GMT Re:Re-rolling 1's and statistics
But in general, yeah it amounts to +1/6 the number of expected successes for that roll (so if you were expecting 6 hits, now it's 7). So in general you want to use it either on lots of dice, or on stuff that already has a high success rate.

Note that all other things equal though, re-rolling hits is better than re-rolling wounds. Because hits have a larger dice pool, which gives more opportunities to re-roll, which pushes more total dice down the line. Re-rolling wounds is for things that auto-hit, or that are already re-rolling hits (because you can't re-roll the same roll twice).

But if your wound-roll has a significantly higher success rate than your hit-roll (like 4+ to hit and 2+ to wound), you'll probably want to re-roll 1s on the 2+ because it'll multiply the already-high success rate. If you have a full re-roll available you might want to put it on the 4+, because it'll benefit more from being able to re-roll 2s and 3s, and push more dice to the wound stage. ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435957.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435957.page GMT Re:Re-rolling 1's and statistics
 ross-128 wrote:
That depends on what you mean by "what it would otherwise be".
I meant that, say there's a 1/4 average chance that a given attack forces a save. A re-roll of 1 to hit or 1 to wound will in both cases move that average to 7/24?]]> http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435987.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435987.page GMT Re-rolling 1's and statistics http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435993.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9435993.page GMT Re-rolling 1's and statistics http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436009.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436009.page GMT Re:Re-rolling 1's and statistics
The chance of rolling a 1 is always 1/6. If you make that 1/6 you then have a X/6 chance of getting a success. So your statistic is 1/6(x/6). For example for a 3+ you have a 1/6(4/6) chance of success after rolling a 1. Or .111.

You can add these two together giving the equation (X/6) + (1/6)(X/6). For our example of 3+ you have (4/6) + 1/6(4/6) which is about .778.

You can simplify the equation. (X/6) = (6/6)(X/6) when you put that in the equation you get (6/6)(X/6)+(1/6)(X/6) = (7/6)(X/6)

So we see that the chance of a success when rerolling 1's is equal to (7/6) times the normal success rate. ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436034.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436034.page GMT Re:Re-rolling 1's and statistics
But in general, yeah, it's close enough. ]]> http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436042.page http://www.dakkadakka.com/dakkaforum/posts/preList/729129/9436042.page GMT