Possible reinforcement bug in v1.1B24

[StellarRat]

I have a scenario that I've designed where there is a 2% each turn of reinforcements arriving and five possible types of reinforcements (after turn 1.) In other words each turn the game should try five times to "roll" a 2% or less and depending on which reinforcement gets the roll I may get one of five different types of tanks as reinforcement (or I could get multiple reinforcements in one turn if I'm really lucky.) The problem is that I've played the scenario at least 20+ times now and I've NEVER gotten the reinforcements before turn 25. Is the chance cumulative? The reinforcements always seem to arrive around turn 25 or later (out of 30 turns.) The other weird thing is that I ALWAYS seem to get some reinforcements. It seems that there should be a good chance that nothing will show up for the entire game.

I would think if the chance wasn't cumulative they would arrive at various times during the game not just towards the end. I didn't notice this problem in v1.05.

I've submitted a bug report for v1.1B24. Has anyone else noticed this?

[Maximus]

I think the percentages *are* cumulative. Although I may be mistaken.

[dNorwood]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Maximus:

I think the percentages *are* cumulative. Although I may be mistaken. <HR></BLOCKQUOTE>

Manual p. 132 - "Example: A unit is set for "first possible arrival" of turn 4, with a "chance" of 30%. ..[etc]...It has a 30% chance to arrive on turn 4. If it does not arrive on turn 4, then it has a 30% chance to arrive on turn 5..[etc].."

So, a 2% chance (per turn) of reinforcement has a 40% chance of arriving before turn 25 (and obviously a 60% chance of arriving thereafter). The multiple types of reinforcment make the problem more complex - my gut tells me that you get a 50/50 chance of reinforcement before turn 25.

[This message has been edited by dNorwood (edited 12-27-2000).]

[Guest aaronb]

<BLOCKQUOTE>quote:</font><HR>Originally posted by dNorwood:

Manual p. 132 - "Example: A unit is set for "first possible arrival" of turn 4, with a "chance" of 30%. ..[etc]...It has a 30% chance to arrive on turn 4. If it does not arrive on turn 4, then it has a 30% chance to arrive on turn 5..[etc].."

<HR></BLOCKQUOTE>

Ok, it works like this.

n = percent chance of arrival on a given turn

t = number of turns that go by

p(a,t) = the chance of arrival before or on turn t

If each turn is independent of the one before it (unlike weather, where a sunny day skews the next day's weather, loosely speaking), then:

p(a,t) = 1-(1-n)^t

E.g., on the first turn, if the chance of arrival is .4 (40%):

p(a,1) = 1-(1-.4)^1

p(a,1) = 1-(.6)^1

p(a,1) = 1-.6

p(a,1) = .4, as we would expect.

So, if there is a 2% chance each turn (and the manual says it is not cumulative), then:

p(a,25) = 1-(1-.02)^25

= 1-(.98)^25

= 1-0.60346473

= 0.39653527

or about 40%.

This is exactly what dNorwood said. I've just given the formula so you can do the math for yourself.

------------------

my armoured assets have about the half-life of a gnat in DDT

- Germanboy

[StellarRat]

<BLOCKQUOTE>quote:</font><HR>Originally posted by aaronb:

Ok, it works like this.

n = percent chance of arrival on a given turn

t = number of turns that go by

p(a,t) = the chance of arrival before or on turn t

If each turn is independent of the one before it (unlike weather, where a sunny day skews the next day's weather, loosely speaking), then:

p(a,t) = 1-(1-n)^t

E.g., on the first turn, if the chance of arrival is .4 (40%):

p(a,1) = 1-(1-.4)^1

p(a,1) = 1-(.6)^1

p(a,1) = 1-.6

p(a,1) = .4, as we would expect.

So, if there is a 2% chance each turn (and the manual says it is not cumulative), then:

p(a,25) = 1-(1-.02)^25

= 1-(.98)^25

= 1-0.60346473

= 0.39653527

or about 40%.

This is exactly what dNorwood said. I've just given the formula so you can do the math for yourself.

<HR></BLOCKQUOTE>

So, based on what your telling me I believe there is a bug here. In 20+ games I should see reinforcements before turn 25 and some games no reinforcements ever. With a 40% chance (by your calcs) the odds against not getting reinforcements before turn 25 in 20+ games is huge. Also, there should be games where I get no reinforcements, this is also not happening.

[Guest aaronb]

<BLOCKQUOTE>quote:</font><HR>Originally posted by StellarRat:

So, based on what your telling me I believe there is a bug here.<HR></BLOCKQUOTE>

I'm telling you the odds as indicated by the manual - if the behaviour you have seen is a bug, and it may be, then maybe Matt needs to see a save file that shows this behaviour.

[StellarRat]

Matt has tested this and it seems to be working correctly. I may have been very, very unlucky up to that point. After I made the post here I retried the scenario after checking the percentages and resaving it and got reinforcements on turn 6 and turn 10. Matt is looking into the possibility of a problem with scenarios that were saved in 1.05 and played in the betas.