Why One Minimally Trades: ROI

[aardvarkpepper]

Today I spoke with someone on Discord and mentioned ROI in context of trades in some situations in KJF. They didn’t know what I meant. Shocking.

Well, the nature of the internet is such that sometimes subjects will have to be revisited, people forget what used to be known, and so on.

Here I’m going to try something new. Instead of putting everything on display, I’m just going to hit a few sharp notes, and maybe readers that are really paying attention will be “hey but what about -”

Figure it out yourselves. Or wait until I maybe finish up a series of articles, I don’t know sometime.

Okay, anyways minimal trades and ROI.

The basic idea is, you trade minimally, why? Because of ROI.

Say you have 1 fighter 1 infantry attacking 1 infantry for control of a 2 IPC territory.

What happens when you add 1 infantry to attackers?

You get slightly higher probabilities of destroying the enemy infantry without sustaining a loss, slightly higher probability of capture. But the next expectation is, I forget, say +0.3 IPC. Because the attacking 1 infantry 1 fighter already had pretty good chances; padding the attack a little more doesn’t make that much of a difference.

Now let’s say you have a battle of over 200 IPC counting units on both sides. What happens when you add one artillery to attacker?

Depends on compositions, but you can get something like +20 IPC. Not looking at my notes at the moment. Something stupid anyways.

So you contrast 10% ROI (return on investment) and 500% ROI. You can see how 500% ROI is much better.

Why? The first round, the artillery can inflict a casualty on a defender. Not for sure, but there’s a chance. That defender won’t be around for the second round of fire. So that defender can’t destroy another attacker, and that attacker in turn could destroy more defenders. The whole thing snowballs.

And battles last, I forget, something like a bit more than 6 turns on average even for major stack battles, depending on composition of course but still. What with dice bunching up here or there, and only needing so-much-value to hit, that’s about what it works out to.

So what you see is a cumulative effect; even though we’re only talking about percentages instead of a sure thing, the aggregate probability over time and cumulative effect results in much higher ROI.

And if you send more units to the front for trades (as opposed to stacking something that isn’t intended to be attacked at all), then often that just means your opponent gets more opportunity to pull a favorable ROI attack on the units that were made vulnerable.

Yes there’s exceptions and such. But be very wary of writers that post stuff like “because top platinum says so”. There are mathematical reasons that can be explained and demonstrated that show exactly when and how the above does not apply, and understanding how to make that distinction is what separates weak players from strong players.