From: elk@cbnews.cb.att.com (edwin.l.king)
Newsgroups: rec.games.frp
Subject: GURPS Combat Odds (was GURPS Combat Time)
Date: 11 Apr 92 13:03:45 GMT
Organization: AT&T

In a previous posting, I had mentioned the notion that under quick
contest rules, the inflation of combat skills is an easier thing to
control than otherwise, because the odds work out such that it will
balance at most any skill level.

Here are the charts we worked out to show this.  This posting is
pretty long, but I didn't see much way to cut it down.


DIE PERCENTAGES
-----------------
                             1d              2d              3d
		Roll  Chance	Cum.	Chance	Cum.	Chance  Cum.
		----------------------------------------------------
                  1:	17%	 17%	
		  2:	17%	 33%	   2%    2%	
		  3:    17%	 50%	   5%    8% 	  <1%    <1%
		  4:    17%	 67%	   8%	16%	   1%     1%
		  5:    17%	 83%	  11%   27%	   2%     4%
		  6:    17%	100%	  13%   41%	   4%     9%
		  7: 			  16%   58%	   6%    16%
		  8:     		  13%   72%        9%    25%
		  9:    		  11%   83%       11%    37%
		 10:    		   8%   91%       12%    50%
		 11:    		   5%   97%       12%    62%
		 12:    		   2%  100%       11%    74%
 		 13:     				   9%    83%
		 14:     				   6%    90%
		 15:     				   4%    95%
		 16:     				   2%    98%
		 17:     				   1%    99%
		 18:     				  <1%   100%


ARMOUR PIERCING ODDS
--------------------
(that is, if you do X amount of damage, what are your odds of getting
at least 1 point of damage through the DR?  For higher damages,
mentally increment the DR by one. e.g. doing 2 pt against DR 0 has the
same chance as doing 1 pt against DR 1.)

				       DR
Damage|	0	1	2	3	4	5	6	7	8
------+------------------------------------------------------------------
 1d-3 |50	33	17
 1d-2 |67	50	33	17
 1d-1 |83	67	50	33	17
 1d   |100	83	67	50	33	17
 1d+1 |100	100	83	67	50	33	17
 1d+2 |100	100	100	83	67	50	33	17
 1d+3 |100	100	100	100	83	67	50	33	17
 1d+4 |100	100	100	100	100	83	67	50	33
 1d+5 |100	100	100	100	100	100	83	67	50
 1d+6 |100	100	100	100	100	100	100	83	67
 2d-3 |91	83	72	58	41	27	16	8	2
 2d-2 |97	91	83	72	58	41	27	16	8
 2d-1 |100	97	91	83	72	58	41	27	16
 2d   |100	100	97	91	83	72	58	41	27
 2d+1 |100	100	100	97	91	83	72	58	41
 2d+2 |100	100	100	100	97	91	83	72	58
 2d+3 |100	100	100	100	100	97	91	83	72
 2d+4 |100	100	100	100	100	100	97	91	83
 2d+5 |100	100	100	100	100	100	100	97	91
 2d+6 |100	100	100	100	100	100	100	100	97
 3d-3 |100	99	98	95	90	83	74	62	50
 3d-2 |100	100	99	98	95	90	83	74	62
 3d-1 |100	100	100	99	98	95	90	83	74
 3d   |100	100	100	100	99	98	95	90	83
 3d+1 |100	100	100	100	100	99	98	95	90
 3d+2 |100	100	100	100	100	100	99	98	95
 3d+3 |100	100	100	100	100	100	100	99	98
 3d+4 |100	100	100	100	100	100	100	100	99
 3d+5 |100	100	100	100	100	100	100	100	100


Attack/Defense Odds

 A|                     Effective  Attack Skill
 D|  3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
  +---------------------------------------------------------------
 3|  0   0   2   7  14  23  35  47  60  71  81  88  90  91  92  93 
 4|  0   0   2   7  14  23  35  47  59  70  80  87  89  90  91  92 
 5|  0   0   2   7  13  22  34  45  57  68  78  84  86  87  88  89 
 6|  0   0   2   6  13  21  32  43  55  65  74  80  82  83  84  85 
 7|  0   0   2   6  12  20  29  40  50  60  68  74  76  77  78  78 
 8|  0   0   2   5  10  17  26  35  44  53  60  65  67  68  69  69 
 9|  0   0   1   4   8  15  22  30  37  45  51  55  56  57  58  58 
10|  0   0   1   3   7  12  17  24  30  36  40  44  45  46  46  46 
11|  0   0   1   2   5   9  13  18  22  27  30  33  34  34  35  35 
12|  0   0   0   1   3   6   9  12  15  18  21  23  23  24  24  24 
13|  0   0   0   1   2   3   5   7   9  11  13  14  14  15  15  15 
14|  0   0   0   0   1   2   3   4   5   6   7   8   8   8   8   8 
15|  0   0   0   0   0   1   1   2   2   3   3   4   4   4   4   4 
16|  0   0   0   0   0   0   0   0   1   1   1   1   1   1   1   1 
17|  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0 
18|  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0 


 Quick Contest Odds
                                  Your skill

       3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20 
   +------------------------------------------------------------------------
  3|  50  60  69  77  83  88  92  94  95  96  96  96  96  96  96  96  96  96 
  4|  39  50  60  69  77  83  88  92  94  95  96  96  96  96  96  96  96  96 
  5|  30  39  50  60  69  77  83  88  92  94  95  96  96  96  96  96  96  96 
  6|  22  30  39  50  60  69  77  83  88  92  94  95  96  96  96  96  96  96 
  7|  16  22  30  39  50  60  69  77  83  88  92  94  95  96  96  96  96  96 
  8|  11  16  22  30  39  50  60  69  77  83  88  92  94  95  96  96  96  96 
  9|   7  11  16  22  30  39  50  60  69  77  83  88  92  94  95  96  96  96 
 10|   5   7  11  16  22  30  39  50  60  69  77  83  88  92  94  95  96  96 
 11|   4   5   7  11  16  22  30  39  50  60  69  77  83  88  92  94  95  96 
 12|   3   4   5   7  11  16  22  30  39  50  60  69  77  83  88  92  94  95 
 13|   3   3   4   5   7  11  16  22  30  39  50  60  69  77  83  88  92  94 
 14|   3   3   3   4   5   7  11  16  22  30  39  50  60  69  77  83  88  92 
 15|   3   3   3   3   4   5   7  11  16  22  30  39  50  60  69  76  83  87 
 16|   3   3   3   3   3   4   5   7  11  16  22  30  39  50  59  68  75  81 
 17|   3   3   3   3   3   3   4   5   7  11  16  22  30  40  50  59  68  75 
 18|   3   3   3   3   3   3   3   4   5   7  11  16  23  31  40  50  59  68 
 19|   3   3   3   3   3   3   3   3   4   5   7  11  16  24  31  40  50  59 
 20|   3   3   3   3   3   3   3   3   3   4   5   7  12  18  24  31  40  50 



APPLICATION
-----------
OK, what are yours odds or hurting someone in plate mail?

    1) Find your odds of hitting them (use appropriate chart, above).
    2) Find your odds of doing them any damage. (see armour piercing
       chart)
    3) Multiply the two numbers.
    4) Divide by 100.

Example: Sir George has sword skill of 16 (15 in plate), PD 4, DR6.
	 After modifiers, his total parry is 16.  He does 2d+1
	 damage on a swing.

	 Evaine has rapier skill of 17; PD5, DR1.  After modifiers,
	 her parry is 16.  She does 1d damage with it.

	 George's chance's of hitting Evaine AND DOING DAMAGE
	 (under quick contest rules) are 50*100/100 == 50%.

	 Evaine's chances of hitting George AND DOING DAMAGE are
	 0 for a torso shot.  If she takes an eyeslit shot, she can
	 get it to 3%.

Example: Two street thugs are hacking it out with daggers.  They are
         both decent with their knives, say skill 12.  Both do d+1
         damage, and are wearing leather jackets -- PD 1, DR 1.

	 That'll give them a dodge of about 8 + 1 for 9.

         They each have a 77% chance of hitting and a 100% chance of
         penetrating under quick contest rules.

         As an aside, under the regular system, those odds would be
         still a 100% of penetrating, but only a 45% chance of
         hitting.

	

 
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