Determining a successful reaper harass

How many worker kills does your initial reaper need to kill to justify its cost?

Is it as simple as the reapers cost in kills? (2 workers?)

If I get 3-4 kills I'm happy, (if I kill 1 mule it's great too). I'd to know if anyone actually has a firm confirmation on this.

The reason why I wanted to bring this up, is especially on a TVT. I hate building my first reaper cuz of the 50 gas + tech lab. I'd rather save that gas for my first vikings or banshees. If I'm going to invest in a reaper, I want to know how many kills I'd need to get for it to be justified

But then, I'd lose matches anyway because 1 marine sucks when it's trying to defend your worker line.

Well I generally I do Crota's reaper build, which is 9rax reapers... Generally pumping 3 while using the first to harass works very well, you can kill alot of workers, force them to consider going maruders and definitely justify your cost.

I'd have to say thou probly 3-4 workers justifies one reaper depending on how many SCVs they have vs how many army units. If you want to see some examples of reapering you can always check out crota's (or mine link below) shoutcasts where reapers are exampled and how they justify their cost.

This depends on facets not only alone on the unit cost. Think about it this way, if you have a reaper gaining information you don't need to make an SCV. That means that you can quantify it's success in the following ways.

1. If you typically lose your first SCV when scouting (Some of us do!) then you have to remember that the first SCV you'd kill with a reaper is a benefit to you, not "catching up".
2. At core, killing 2 mineral scvs is acceptable, 1 scv on gas is very beneficial (cause they typically don't put another scv on right away)
3. If you pull their scvs off the mineral line, you "break even" for the cost by this action alone pending how long they are off minerals. Example, if you manage to pull 12 scvs off the line, you justify the cost of your reaper after 9 seconds, even if you don't get a single kill and still live. (9x12=~100 minerals not mined during that time) This becomes even more relevant if they don't get gas during this time they were depending on.

This doesn't even cover the ability to gain information on them and the ability to direct their retaliation in a fashion that you can easily predict.

Funny you should bring this up, I was working on an equation for loss of minerals based on numbers of SCVs last night. I think there's a much simpler way to write it, maybe an exponential decay, but I don't know how.

A=(17x)+(17(x-1))+(17(x-2))...(17(x-x))+50x

A=amount of minerals lost total.
x=amount of scvs killed.

Starting at the mineral field scvs mine 60 minerals a minute, that means 1 mineral a second, scvs take 17 seconds to build, + 50 for the actual cost of the scv. So kill 4 scvs, and for 17 seconds while they build the first replacement, the loss of money in time alone is 17x=A when x=4. That comes out to 68, now when the second scv is building the loss is less, x will still me 4 for math purposes, but minus 1. So 17(x-1)=A, 17(4-1)=51. You keep that pattern up until you hit x-x, and the last scv is build, which is only a loss of 17. Finally you add 50x for the actual cost of each scv.

The cost of a tech lab is 50 minerals , but 50 more for the first reaper, it comes out to 100, plus 75 gas. It's very easy to get your money's worth, kill just two scvs and you've set them back 151 minerals, kill 3 and it's 252, four is 370. This is really brutal to other terran early on, I recommend you keep it up.

Against Protoss and Zerg it's a much harder calculation, because of factors like how many drones the zerg can respawn at once, and how much chrono-boost energy the Protoss has. Over-all though I would say keep it up, micro well and your pretty much guaranteed to get your money's worth. The equation I gave is best case scenario for the enemy, they're not going to be instantly producing another worker, they probably won't until you leave, not to mention the enormous dent you can leave by forcing the workers off the line. Every second lost for every worker is another mineral, force 16 workers off the line to trap your reapers for 5 seconds, and it's 80 minerals you cost them, even at the cost of your reapers, add in the kills you get while the scvs are on you and you come out on top. All the factors I didn't calculate cannot do anything but work in your favor.

Quote:

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Originally Posted by Roland

Funny you should bring this up, I was working on an equation for loss of minerals based on numbers of SCVs last night. I think there's a much simpler way to write it, maybe an exponential decay, but I don't know how.

A=(17x)+(17(x-1))+(17(x-2))...(17(x-x))+50x

A=amount of minerals lost total.
x=amount of scvs killed.

Starting at the mineral field scvs mine 60 minerals a minute, that means 1 mineral a second, scvs take 17 seconds to build, + 50 for the actual cost of the scv. So kill 4 scvs, and for 17 seconds while they build the first replacement, the loss of money in time alone is 17x=A when x=4. That comes out to 68, now when the second scv is building the loss is less, x will still me 4 for math purposes, but minus 1. So 17(x-1)=A, 17(4-1)=51. You keep that pattern up until you hit x-x, and the last scv is build, which is only a loss of 17. Finally you add 50x for the actual cost of each scv.

The cost of a tech lab is 50 minerals , but 50 more for the first reaper, it comes out to 100, plus 75 gas. It's very easy to get your money's worth, kill just two scvs and you've set them back 151 minerals, kill 3 and it's 252, four is 370. This is really brutal to other terran early on, I recommend you keep it up.

Against Protoss and Zerg it's a much harder calculation, because of factors like how many drones the zerg can respawn at once, and how much chrono-boost energy the Protoss has. Over-all though I would say keep it up, micro well and your pretty much guaranteed to get your money's worth. The equation I gave is best case scenario for the enemy, they're not going to be instantly producing another worker, they probably won't until you leave, not to mention the enormous dent you can leave by forcing the workers off the line. Every second lost for every worker is another mineral, force 16 workers off the line to trap your reapers for 5 seconds, and it's 80 minerals you cost them, even at the cost of your reapers, add in the kills you get while the scvs are on you and you come out on top. All the factors I didn't calculate cannot do anything but work in your favor.

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Woah...I don't get that at all.

Ha, it's not too bad, look at it this way, there are two ways someone loses money when an scv is killed, first is by the cost to replace it, and secondly the minerals it would've mined had it not been killed. SCVs mine 1 mineral per second, and take 17 seconds to build. So if you kill one scv the lost is 50+17=67.

Now, you can't just multiply that for every scv you kill, because you can only build 1 scv at a time, meaning that for every scv you kill it takes longer to replace the total for your enemy, and the loss gets exponentially higher, as it takes longer and longer to replace the total number of workers, and therefore the time that would be spent mining increases, along with the total loss. Here's an example of total loss if I killed 3 scvs.
A=(17x)+________(17(x-1))+_____________(17(x-2))...(17(x-x))+50x (equation)
(1st scv) (2nd, 1st mining creates the "-1") (3rd, 1st 2 mining creates the -2, and so on until you multiply by 0)


A=(17(3))+(17(3-1))+(17(3-2))+(17(3-3))+50(3)
A=51+(17*2)+(17*1)+(17*0)+150
A=51+34+17+150
A=252

Ok. Now that makes more sense to me for some reason.

Have to admit, my understanding of mathematics ends at basic Algebra. :)

Thats a rather awesome calculation; iv actualy wondered how long worker units take to pay for themselves by mining, and iv also done alot f reaper harass lately.. so yeah....

your equation is wrong because theres a time factor
time mining lost from having scv dead and time mining gained after scv is made
i think it should cancel itself out but to do it would require time

other factors that can potentially affect this is the distance to each field and number of workers, more workers less each worker can mine in a time period because it has to move and field if occupied

A = dx/dy = #x^n + y

If you know how to read this equation, you will get how effective is your attack.

y = time
x = number of SCVs lost
n = exponential lost of minerals over time "ex: 15 minerals / 10 seconds"
# = cost for units lost

Yes I'm trolling you, but will indeed attempt to fit some mathematics into SC2 for a Calculus class project XD, If you can't fight it join it! I swear that I want to know more about derivatives now that I know I can relate them to starcraft XD