Marines & City Defenses - Any Bonuses?

[Catt]

I have read several posts on various random threads (many over at CivFanatics) that include the assertion that when marines attack amphibiously, the city defenders do not get the city defensive bonus (50% for a city and 100% for a metropolis) or the defensive benefits of Walls if the "city" is a town that has built walls. I don't know if this is correct or not, but I can't find any evidence supporting this.

Does anyone know if this is true (that defenders do NOT enjoy a city defense bonus), and if it is true, how do do you know it's true?

Thanks!

Catt

[Sava]

Defenders do get the bonus.... go to http://www.columbia.edu/~sdc2002/civulator.html

It lets you simulate any battles.

[ChaotikVisions]

How are the results determined for the civulator? It can't be entirely accurate.

[Catt]

Sava, thanks for the reply, but I think the civulator is just a calculator. It doesn't answer the question of whether or not the defenders get the bonus (since the user selects the applicable defensive bonus options).

I do think that the defenders get the bonuses (i.e., that an amphibious assault is just like a land-based assault), but only because I don't see any "official" (i.e., manual, civolopedia (sp?), or Firaxian comment) confirmation, nor a posted experiment that demonstrated, beyond statistical doubt, that marines were winning far more battles than would seem normal.

OTOH, I don't know that the defender gets the bonus, and I have seen the view expressed so many times, that I wonder if I'm just missing something, or whether this truly is an urban civilization myth.

Catt

[Whoha]

Think it does give a bonus, without any modifying of stats, marines will suffer absurdly large casualty rates, Of course that might just be the 10 defense infantry vs the 8 attack marines, dont know, changed it to 14A 12D for marines.

[Panag]

Originally posted by ChaotikVisions
How are the results determined for the civulator? It can't be entirely accurate.

hi ,

who made the calculator , ........

have a nice day

[notyoueither]

My observations agree with the reduced defense bonus line of thought.

Landed in a metropolis with Marines. There were 3 Infantry defending (2 full strength Vet, 1 Vet with 2 pips left). I lost 3 Marines in taking the city.

[Panag]

Originally posted by notyoueither
My observations agree with the reduced defense bonus line of thought.

Landed in a metropolis with Marines. There were 3 Infantry defending (2 full strength Vet, 1 Vet with 2 pips left). I lost 3 Marines in taking the city.

hi ,

you should have used airpower or naval power first , .....

sometimes you lose 3 vet mar to a reg rifleman , but this has to do with some weird calculation , .......

have a nice day

[FrantzX]

That's why I want this: http://apolyton.net/forums/showthrea...threadid=52037

[Panag]

Originally posted by FrantzX
That's why I want this: http://apolyton.net/forums/showthrea...threadid=52037

hi ,

it should go further then that , it should go way further , .....

have a nice day

[Catt]

Okay -- I managed to set up and run a test to determine whether defenders lose their city defense bonuses when facing amphibious assaults. The answer (definitive, in my view) is that they do not. In other words, city defense bonuses apply to defenders, even when being attacked amphibiously by marines.

First, the test results:

Situation: marines attacking from a transport. Defender is an infantry, fortified in a metropolis (size 14), built on grassland. Assuming all defensive bonuses apply, the infantry defense should be 23.5 (base of 10, bonuses as follows: 100%+25%+10%, from metropolis, fortification, grassland respectively). With an attack value of 8, we would expect the marine to win 25.40% of the individual combat die rolls (i.e. hit point lost by attacker or defender).

Actual test results:

2501 individual combat die rolls
1867 HPs lost by marines
634 HPs lost by infantry

Empirical marine success rate: 25.35%

Someone who actually took statistics and remembers the experience can comment on whether 2500 trials is sufficient to give comfort -- it certainly is for me.

Catt

[For those who wish to understand how I conducted the test, details here.]

[dexters]

Heheh Catt, you need far fewer than 2500 to have 99.9 % confidence

Can't remember the specifics as I need to refer to my stats notes, but something about normal distribution, and standard deviation

[vulture]

Originally posted by Catt

First, the test results:

Situation: marines attacking from a transport. Defender is an infantry, fortified in a metropolis (size 14), built on grassland. Assuming all defensive bonuses apply, the infantry defense should be 23.5 (base of 10, bonuses as follows: 100%+25%+10%, from metropolis, fortification, grassland respectively). With an attack value of 8, we would expect the marine to win 25.40% of the individual combat die rolls (i.e. hit point lost by attacker or defender).

Actual test results:

2501 individual combat die rolls
1867 HPs lost by marines
634 HPs lost by infantry

Empirical marine success rate: 25.35%

Someone who actually took statistics and remembers the experience can comment on whether 2500 trials is sufficient to give comfort -- it certainly is for me.

Catt

Using the standard binomial results, the standard deviation for your results is +/- 21.8, so you success rate becomes (25.35 +/-0.87) % with 68% confidence (although the confidence interval isn't really symmetric about the value you derived). From this you can work out the 68% confidence limits for the city defensive bonus, and it gives you 90%-112%, with the actual value from the data being 101%.

The data are sufficient to reject the hypothesis that the city defense bonus is reduced to 50% or less (size 12 or less city) at about the 5 sigma (>99.99%) confidence level.

[Panag]

hi ,

a Q , is in this result the option of the status calculated , .....like elite , .....

have a nice day

[Catt]

Originally posted by panag
hi ,

a Q , is in this result the option of the status calculated , .....like elite , .....

have a nice day

No - in my test mod, all experience levels (conscript through elite) have the same number of hit points. See the test structure in the link several posts above.

Catt