Thursday, February 25, 2010

Evaluating Units Honestly: Opportunity Cost

Aside from being a stupidly catchy song and amusing video, the song emphasizes a point: "You can go with this, or you can go with that," (Or you can blow it up, but we're trying that too, aren't we?). Blame Haihastur too for this one, since he touched on it in the comments here.

Defining the Term
'Opportunity cost' is a $20 term you'll hear in economics class that explains the idea that 'there is no such thing as a free lunch.' So, let's say someone buys you lunch. You spend time, go with them, eat, and may or may not enjoy yourself, the food, the company, etc. Right? Perfectly plausible.

See, the thing is that the lunch never cost you MONEY, but you still had to spend the time. You could have eaten somewhere else with different company, or simply worked through lunch and gone home early that day (assuming your workplace would let you).

The fancier definition is that when you pick one option, the opportunity cost is what you give up from the second best option. IE: I have $1 and a vending machine. I can buy a Nutty Bar (mmm, peanut butter and chocolate...) or a Coke (mmm, cleans engine parts AND refreshes!). If I buy a Nutty Bar, the opportunity cost was the coke. If I buy a coke, the opportunity cost was the Nutty Bar. If I don't buy anything, the cost of $1 was not eating from the vending machine.

Make sense?

Opportunity Cost in 40k Terms
Let's walk away from the vending machines in the break room and look at the force organization chart. I'm allowed 2 HQ choices, 3 elites, 6 troops, 3 fast attack, and 3 heavy support. I'm also allotted a certain amount of points per game, and I'll generally have to field one HQ and two troops selections.

We'll have to compare Opportunity Cost two main ways in 40k: force org slots and points.

Force Org Slots
Here, we're comparing options within a given force organization slot. Well, we have to have an HQ, and we have to have two troops (and will often go for at least a third, depending on the army). These are non-negotiable slots, so what we put in them is part of the army's 'theme' (in that you want something like light or heavy mech, or foot, or massed MCs, or horde, or whatnot).

Similar Roles
Here, we're talking support. It's simple, because we can limit our comparison to the slot. This is where Haihastur started this. If I recall correctly, he's not a fan of Vindicators in the Marine codex (and frankly, I'm not either), but prefers Whirlwinds to Predators.

Well, we have 3 heavy support slots, and we probably want to at least duplicate the choice for sake of reliability/resiliency (aka, redundancy). So, we're comparing the capabilities of two potentially disparate units. We should ask ourselves:
1) What capabilities does it bring/what does it kill?
2) What does this do for the rest of my army, potentially?
3) What's the point cost?

The Heavy Bolter/Autocannon Predator is more or less the same price as the Whirlwind, so price isn't an option. We then need to ask what do they do, and what do they bring for the army. This is a nutshell example, so I'm not going to give you all a full Vindicator vs Predator comparison. Short version:

-Worry light armor w/ heavy bolters, autocannon
-worry medium armor w/ autocannon
-durable AV13-front vehicle; one more target to deal with
-worry monstrous creatures & infantry, but loses effectiveness to cover

-maim up infantry w/ S4, AP5 ignores-cover shot
-prefers to hide
-single weapon system = one damage result to gimp it.

My opinion leans towards the predator because it can do more than the Whirlwind (engage vehicles/MCs/infantry), even though the Whirly can scare lighter infantry even if it's in cover (assuming they're AP5) and can still respectably wound heavier infantry with the S5 shot.

Disparate Roles
So, let's look at Fast Attack for Space Wolves. They can bring the respectable space marine land speeder, but also have Thunderwolf Cavalry. Both need to be brought in numbers, so they generally preclude the other. Here, we're talking about something that potentially flavors the army; bringing 10-15 thunderwolvs is a hefty points investment and makes them the centerpiece of the army (and they can be a bloody scary one at that).

A tyranid example would be 2-3 Tyrannofexes versus 3 trygons. Taking Tyrannofexes means you've got a ranged shooty core to the army, whereas 3 Trygons means you're going to be in the enemy's face and that'll dictate how you build the army.

The same can easily be said for any Space Marine commander with Chapter Tactics in lieu of combat tactics, or any strong supporting HQ figure (IE: Farseers for psychic support/defense, Hive Tyrants for reserves manipulation/preferred enemy, etc.)

Comparing Capabilities
The other basic form of opportunity cost comes in the form of similar capabilities in different slots. This is something you'll find more of in newer codices, as this allows you much greater flexibility in terms of making an army, but complicates army building a bit since you're weighing more options. (I'll take the extra work, personally).

Let's look at the IG book. I don't know about you guys, but I like poofing infantry in great bloody swathes. Do you like that? I also like chunky spaghetti sauce, but that's unrelated.

So, if I want to KO swathes of infantry, I have several choices, including:
1) Hellhounds in Fast Attack
2) Valkyries with Missile Pods in Fast Attack
3) Multiple Chimeras w/ Hull Heavy Flamers in troops, other slots
-possibly Platoon Commands in aforementioned chimeras with flamers, too
4) Leman Russ Eradicator in Heavy Support
5) Colossus Siege Mortar in Heavy Support

All of these are capable of doing horrifically graphic things to infantry, though not all capabilities are necessarily equal.

My evaluation will also depend on what other essentially capabilities I can get in other slots, so I'm still doing some intra-slot comparison. I could take Hellhounds (which can get hull multi-meltas for some duality), which means I need to get some more reliable anti-tank elsewhere (Maybe troops or heavy support, but not Vendettas. Maybe Hydra flak tanks and meltagun squads?). Or, maybe I take the Russ Eradicators, filling up my heavy support and leaving me with the need to bring anti-tank in other slots (Maybe vendettas or melta squads?).

Wrapup: Opportunity Cost and Army Design
Basically, you need to start by knowing what your army can give you in what slots. Some armies make this simpler than others. With Eldar, I know I want to bring Fire Dragons to kill heavy tanks, because they're a solid option (...and I don't really have other good options for killing tanks). I can supplement it with S8 guns from transports and falcons, but I just don't have any other comparable punch, so the rest of my army can fall in after these choices are locked in.

On the other hand, better-designed armies can bring the capabilities in various slots. Here's where you have to do the work and take the concept of opportunity cost into account: you want redundancy so SOME of your tools live to do the jobs, so you're going to generally make one choice for the non-troops slots and duplicate it. That's why you need to get a grasp of tradeoffs.

Hopefully, this has been beneficial (or at least thought-provoking), but it seems like tradeoffs are A) a complicated part of army-building at times, and B) sometimes overlooked.


Chumbalaya said...

Great article, it's definitely something worth considering when building up your army or making any decision really.

Max said...

Good article- always figuring out how to cover all of your bases using the tools available is essential to a functional army list. And knowing the difference between a list-warping unit (i.e. Twolves) and a list-enhancing unit (i.e. Hellhound) is always a good thing to dwell on.

Dverning said...

@Raptor: An excellent article. Quite a wall of text (yes, yes, hypocritical), but well worth the read. This is one you should permalink for people.

@Max: "list-warping" and "list-enhancing"? Good terms. I always used selfish and supportive, but I think your usage gets the concept across a little differently. I'm going to add those to my synonyms.

haihastur said...

hehe, this is developping into a very interesting discussion on army list building, probably the most personal skill of competitive players, and the one we devote most of our time to.

I think you touched two very important points of list building in your article :

1) you have 3 mandatory FOCs slots, and 2/3rd of the games revolves around Troops units. Which means what you take for your mandatory Troop choices will mostly define your army.
To give simple examples (not pretending to cover all the considerations to be taken) :
- my SW Troop choices are (surprisingly) grey hunters in rhinos. these guy are though, excel at anti-infantry, and can fend pretty well for themselves if stranded alone.
but god do they lack RANGE ! that's why the rest of my army is more or less long-range/fast heavy support to deal with vehicles and soften infantry.
I could take other excellent rapid fire/close combat units (TWC, swiftclaws or skyclaws) but they would cost a lot, deprive me from my fourth or fifth Troop unit and/or leave me with nothing to handle heavy mech/fast mech correctly.
- my IG Troops are melta-vets (with AC !) in chimeras. good against armored/MC targets, but seriously lacking range (hence the AC !) and anti-infantry.
I guess that's why the rest of my army brings long range heavies (hydras/vendettas/manticore) and short range anti-infantry (12+heavy flammers and 9 flammers).

My point is : the first step towards building a good all-around list is choosing your Troop choices, understand their strong points and their weaknesses, and fill the rest of the list accordingly.
Even if that means not taking the cool overpowered units that everybody else (or at least noobs) have wet dreams about (TWC, leman russ, doom of malantai, etc)

2) also quite important, as you mentionned, is to know what your army can give you in which FOCs slots.
the example that comes immediately to my mind is the anti-tank in the new nid codex :
- yes, you have anti-tank ability in almost all FOCs slots. harpies, carnifexes and tyrannofexes have their use in some builds.
- but honestly, you have two above-averages units in your Elite choices : hive guard and zoans.
besides their obvious strength in terms of weapons, they also are really, really hard to kill.
try fielding 3 zoans with a prime + 3x2 guards with FNP given by tervigons and cover provided by zoans or gaunts.
in most of my games to date, my opponents never killed more than half those models.
and they are cheap. the above is maxed out and still cost you only 570pts (2 tyrannofexes).
for me those two units really hurts the other elite choices, simply because the opportunity cost of those units is loosing one unit of guards or zoans.
(same problem arise for SW Elite choices, where I feel wolf guards, scouts and rifleman dreads are must-take and really kill the lone wolf interest in most builds)

haihastur said...

I think a good follow-up for this article would be an article about what your army needs to be able to do (at least all-comers builds), something the web community as already written much about.
The "know thy ennemy" articles currently on YTTH are a good example. you know, something like :
- being able to stop tranport/stun heavies at range.
- being able to kill heavies quick (fast, close range suicide units).
- being able to kill infantry en-masse
- being able to outmanoeuver or at least deny mobility
(you may have already written about that, hard to remember everything.)

as a closing note, I wasn't comparing whirlwind and dakka preds ;) sorry, poor wording on my side.
I was making two comparisons :
- WW against vindicators, and how most people spam vindicators for their brute force and endurance, while not seeing the real range and reactivity of the WW.
- predators against melta-spam, with people wanting to kill armor at close range, anmd failing against fast vehicles lists where the predator could save them.

FYI, my current heavy-support choices for my SW are 1 WW, 1 Vindic and 1 pred with AC/2LCs. however I'm considering switching the vindicator for my new rifleman dread :)
WW is an old love of mine. almost always played with one and probably always will.
hard to defend against all the (good) points other players make against this tank :
- yes it lacks armors, but honestly it's always sitting in a corner out of LoS and is mostly ignored by my opponents until it's too late. and againt indirect fire it's as tough as your averga predator :p
- yes it deviates, and when it hits a good opponent can lessen the damage inflicted, but most of the time over the course of the game it gets a least one decisive shot.
- yes other units have more brute force (vindics) or can threaten (at least on the paper) more target type (predators).
but still, people need to realise what it means to have undirect 48" range : you don't care about moving to improve your LoS, you just sit there in the middle of the table and choose one ennemy unit anywhere on the table (aside from the far corners) and you give them a big pinning plate.
your dakka pread is no real threat against transport (for them it's more or less a single AC), and might be more efficient against infantry when spaced or out of cover, but you also might have to move to get a clear LoS, exposing yourself and reducing your firepower drastically.
Many of my marines opponents made fun of this old buddy of mine, and some of them were desperately trying to shut it down by the end of the game :)
But I must admit it's more of a personal choice...

(wow, was a bit too long here, even had to break things in two posts)

Raptor1313 said...

Hey, mine had a picture in it. Yours had text AND math! ;)

I think I'm gonna steal your descriptions for units. It's just compact and descriptive.

It's still all your fault ;)
With 'nids, I hear you 100%. I think Venomthropes could have their place in a horde build as long as you're judicious with placement.

I've taken a shot at doing a 'what you need' article before, and I think I'll probably try it again springboarding off this one.

I think you bring up a good point about the Whirlwind in terms of psychological warfare. Psych warfare doesn't work all the time, but there IS a certain amount of frustration involved in a unit hiding and blasting your guys.

Vindies...they don't even have that much brute force if you play against them right and do things like, oh, get cover.

I'll say that with 3 dakka preds, though, you do get a little bit of ranged anti-tank with six S7 shots at BS4. Might actually down a tank when fired en-masse! Might. But, it's a capability to have.

Matt Varnish said...

One thing I will throw into the ideas here is that of psycological units. I sometimes use units that while on paper, the points spent could be used more wisely, yet bring a fear factor to my opponents.

My outflanking genestealers for example, I have kept a mental track of how they have done/what they have killed, and they are really not that great. Yet they dictate how my opponent deploys in every game because of the threat they pose. Tyrannofex is in the same boat, they know its tough to kill, and stay away from it, despite the fact that it cant hit the broadside of a barn. I used to be a bit of a tool back in the day and as I took my models out of my case, would put 3 lictors on the table first, so my opponent could see them, and then unpack my gear, then put them back in my case... talk about psycological warfare :)

The_King_Elessar said...

It's an excellent article. BUT (there's always a but...) I'm waiting for Part Two!
I want to see you compare Riflemen Dreads and Predators, discussing opportunity cost of missing out on Whirlwinds/Termies etc, and how to factor that in to the creative process of constructing a list. :)

Raptor1313 said...

Ah. Now, I've actually done some articles on that, though I think it's best to pull stuff like that into their own little 'vs' articles. I've got an MM/HF speeder vs MM/HF drop pod dread somewhere, and the speeder vs attack bike.

But, those are a bit more nuanced. Still, I think a 'missing out on some specialists' is worth it; termies and whirlies are both fringe choices that can bring in some benefits, but are potentially army-warping.

The_King_Elessar said...

Oh, I've seen those. :)
For me the difference here is key - they don't compete for FoC slots, but perform the same role, making the opportunity cost much greater as it affects 2 sections of the Dex.
But, if you don't agree I guess I'll just do

Brent said...

Great article... and how the hell (can I cuss here?) do you find the time to write so much quality analysis? Your blogs loaded with it. I particularly like this article though.

I'm taking Macroeconomics now, so the idea of Opportunity Cost seems really appropriate.

I've struggled trying to explain this concept to others; now I've got a way to do so.

Take care - Brent

Raptor1313 said...

Thanks for the glowing praise, Brent. For the opportunity cost, I had a very solid economics professor (...that some other school promptly offered more money; can't blame the guy for leaving).

As for analysis, it's more just a year or so (by now, anyway) of aggregate analysis, and good feedback from commenters.