Gauging Success With KB3

Last Updated 29 April 2001.

This is an outline of how to gauge your probability of success in The KB3 Traveller Task System (and thus what Skill Options to choose), penned by Kenneth Bearden.

You're a Traveller player running a character in a game using the KB3 task system. You're hit with a problem, and you need to make a Task Throw. Under KB3 you have choices - do you use your skill level to throw more dice, lower your difficulty, or raise your Stat to help you attain Greater Success?

Or, in other words, how do you roll the task to your best advantage?


Look at how many dice you're throwing, and look at what the difficulty is. That will tell you all you need to know.

Here are some guidelines as to how to gauge your probability of success.

If you're throwing even dice (1D vs 1D... 2D vs 2D... 3D vs 3D, etc), figure you've got about a 50% chance of succeeding.

1D MORE (70%)
If you're throwing one die more than the difficulty (2D vs 1D... 3D vs 2D... 4D vs 3D, etc), figure your chance of success is about 70%, give or take 5%.
Note: The more dice we're talking about, the lower this number will be (2D vs 1D is 77%... 7D vs 6D is 64%).

2D MORE (80%)
If you're throwing two die more than difficulty (3D vs 1D... 4D vs 2D... 5D vs 3D, etc), figure your chance of success is about 80%, give or take 5%.
Note: The more dice we're talking about, the lower this number will be (3D vs 1D is 86%... 7D vs 5D is 74%).

The actual benefit to your throw gets smaller once you've got a 2D lead on your difficulty, and this is the point of diminishing returns. If it is imperative that you make a roll, throw more dice. If you are comfortable with a 80% (or so) chance of success, keep the 2D advantage and use any other skill points for skill options.
Note: Figure a 3D+ advantage over your difficulty gives you about a 90% chance of success (ie 4D vs 1D is 92%... 7D vs 3D is 89%).

A good general target for using your skill options would be to gain a 2D advantage on your difficulty and place the rest of your skill points into either lowering your difficulty number or raising your Stat for measuring purposes. This will net you the best all around benefit from your skills.

SKILL OPTIONS (ie, do you raise your Stat or lower your difficulty?)
This is a judgement call on the players part (part of the fun of the game).
It depends on what you are trying to accomplish. Look at the average of your difficulty (1D average is 3-4; 2D average is 7; 3D average is 10-11; etc), and look at your Stat.
If it doesn't look like you can lower the difficulty under your Stat with your skill options, and rolling Greater Success is important to you on that throw, then raise your Stat for measuring purposes.
On the other hand, if you need help succeeding on the throw, then, by all means, lower your difficulty number (which will also help you a little bit towards Greater Success if the difficulty number is low).
As a SKILL OPTIONS GENERAL RULE, I'd say use your points to lower your difficulty unless the difficulty number is likely to be high. In that case, plan "B" is to raise your Stat.

If you can grasp these easy concepts, you're ready to be a Traveller player using KB3 rules.

The E-Die and the non-intuitive probabilities make the task system scary, but, as you see, it's really simple to gauge your success.

Gauging Success With KB3, copyright © 2001 Kenneth Bearden.
Compiled and edited by David "Hyphen" Jaques-Watson.
Used by permission.

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