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Units attacking from lower ground to higher ground only have a 70% chance to hit Units that are in trees are considered to be "in cover". Any units that are in cover only have a 70% chance of being hit
Or so says Blizzards official strategy guide. But is it really true? It often feels impossible to attack units on high ground, and -30% doesn't seem like that big a deal right?
So since I recently had courses in statistics I thought it would be a fun idea to test the hypothesis about 70% hit-rate.
Gathering data
I made a map where 10 dragoons can attack a missile turret on high ground. Missile turret gets 1000 hp, no armor, and dragoons get to make 1 damage.
I then shot 10 volleys from the goons synchronized and noted the turrets hp.
This was repeated 30 times (restarting map when needed).
Analysis
The goons fired a total of 3000 shots. 1587 hit the target, giving a hit-ratio of 52.9%
What can we then say about the real value p (=probability to hit)?
+ Show Spoiler [Math] +
Well 1587 is an observation of a random variable X from Bin(3000,p).
Since n is 3000, an approximation with the normal distribution will be very accurate.
So X is~ N(3000p,sqrt(3000*p*(1-p)))
So p* = X/3000 is~ N(p,sqrt(p*(1-p)/3000))
and so on...
We can now contruct a ~99.9%-confidence interval for p:
(0.499, 0.559)
This means that the probability that p=(probability for an attack to hit from low to high ground) is somewhere between 0.499 and 0.559 is 99.9%.
Conclusion
It's definatly not a 70% hit rate, at least not on my computer.
It might also be something wrong with starcrafts randomizer in my computer or something 
I also tried the same thing with a tank on high ground and a tank behind a tree. I didn't do 3000 shots, but both cases gave hit-rates around 50% just like with the turret.
I'll upload the map so you can try it yourselves.
>Map from rapidshare
Thanks for reading!
Update
Since many of you thought it might be different for other units I tried the same thing with marines and hydras but with smaller sample sizes, only 500 shots each.
Out of 1000 shots 522 hit giving a hit-ratio of 52.2%
So there's no significant difference between units which is what you'd expect from the programming point of view.
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I always thought something wasn't quite right with the '70% hit' stat, thanks for confirming. :D
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I thought it was 70% chance you miss. I've seen some recent pro games where a goon is shooting a mine on a ramp and it takes roughly 8-12 shots just to hit it once (obviously just a few games).
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Ditto, it always seemed to be much less then 70%. 70% would at least mean if you fire, you have a good chance to hit the unit; I've always seen it around 50% as well.
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I always thought that the unit shooting from low ground has 33% chance of hitting the one higher o.O
and never knew about the trees thing, heh.
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The 70% is definitely not an accurate statistic. Sometimes units rarely miss high ground targets, sometimes they miss almost all their shots. Almost seems like Blizz left that to a random number generator or something to that extent.
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Nice OP. It does feel like less than 70% when playing at times. Blizzard, fix the high ground advantage or change the statistic!
edit- I'm thinking maybe if vision plays some factor, too. Like when you lose vision of the high ground and you can't see your goon shot hit the tank because it disappeared. For example, when a nuke is being dropped, they scan the area so they have vision. Does vision play any role in getting an effective hit?
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It probably would have worked better if you used mutas.
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Highground factors in for everyone except Reach
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I've always felt like that number was a bit high, and it's nice to see someone prove just how ridiculously important high ground is. Chiming in to say great work, OP!
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On February 12 2009 08:49 arb wrote:
Highground factors in for everyone except Reach
Haha~~
+ Show Spoiler +That game was the reason I did this
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On February 12 2009 08:35 ZoW wrote:
The 70% is definitely not an accurate statistic. Sometimes units rarely miss high ground targets, sometimes the miss almost all their shots. Almost seems like Blizz left that to a random number generator or something to that extent.
uh. how else would you do this apart from using a form of RNG?
Interesting OP btw, the sample size and math seem to check out.. looks pretty good that it's not 70%. Maybe it was 70% at one time and changed in a later patch with the guides not updated? i find it hard to believe that blizzard either randomly pulled out a number or just decided to misinform people for fun.
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Nimue would be proud to have you as a student :p
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Finland33997 Posts
On February 12 2009 08:52 JeeJee wrote:Show nested quote +On February 12 2009 08:35 ZoW wrote:
The 70% is definitely not an accurate statistic. Sometimes units rarely miss high ground targets, sometimes the miss almost all their shots. Almost seems like Blizz left that to a random number generator or something to that extent. uh. how else would you do this apart from using a form of RNG? Interesting OP btw, the sample size and math seem to check out.. looks pretty good that it's not 70%. Maybe it was 70% at one time and changed in a later patch with the guides not updated? i find it hard to believe that blizzard either randomly pulled out a number or just decided to misinform people for fun.
I'll check this in the original, non-updated starcraft.
Apparently the 1.00 exe runs at 1.15.3 for me =/ 1.09b has 50% hitrate as well, I don't have any older ones here.
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On February 12 2009 08:52 jtan wrote:Show nested quote +On February 12 2009 08:49 arb wrote:
Highground factors in for everyone except Reach Haha~~ + Show Spoiler +That game was the reason I did this
what game? Link please
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On February 12 2009 08:59 LemOn wrote:Show nested quote +On February 12 2009 08:52 jtan wrote:On February 12 2009 08:49 arb wrote:
Highground factors in for everyone except Reach Haha~~ + Show Spoiler +That game was the reason I did this what game? Link please
+ Show Spoiler +http://www.youtube.com/watch?v=oqSwXOdv2uE&eurl=http://www.teamliquid.net/forum/viewmessage.php?topic_id=50875¤tpage=247
Reach vs Young from today, nothing special but at one point reach attacks uphill and kicks ass
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+ Show Spoiler +I was amazed too but those storms really dealt a lot of damage.. Plus I think young sort of took the high ground safety for granted
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Netherlands13554 Posts
I always thought it was 50%. Never knew about the 70% statistic but I know that can't be right.
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Nice post! Very cool.
Blizzard starcraft guides also mention wraith rushing in TvP is good because you can harass their probe lines. lul.
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EPT![[image loading]](http://img18.imageshack.us/img18/2729/10goonsfm4.jpg)
