Beaker overflow test

[karadoc]

Backstory:
I've heard that there is a research multiplier which boosts your beaker rate while researching techs that other players already have. I've also heard mixed reports as to how beaker overflow works with this multiplier. Do the overflowing beakers have the research bonus from the previous tech, or do they get the multiplier of the tech they are overflowing into?

Anyway, this came up in the funny screenshots thread, and I decided to finally test it.


My test worked like this:
- I bought the tech that I was currently researching from an AI so that I would have zero overflow for the start of the test.
- I set my research to 100%, which was giving me a steady 1030 beakers per turn.
- For the first trial, I researched hunting for one turn and then electricity for one turn so that the hunting research would overflow into electricity. The final beaker count on electricity was 2413.
- For the second trial I skipped hunting and just researched electricity for two turns. The final beaker count was 2474.
- This was done on a normal sized map, with 5 AIs + me. There was originally a 6th AI on the map, but they had already been wiped out. All the AIs had hunting, and none of them had electricity.

Now.. I'm a bit confused by the results. The listed cost of hunting was 62, and the difference between the two final beaker counts is 61, so from that it looks like the overflow from hunting does not get any special benefits. On the other hand, why did I get so many beakers towards electricity anyway? It seems that I'm getting some kind of bonus while researching electricity even though no other civ has it.

To make sure the difference of 61 wasn't just a fluke, I repeated the test with a lower research setting. If the overflow was getting some special bonus, the the effect will be smaller with a lower research setting and so the difference in the final scores should be different... the result was 1316 for hunting->elec, vs 1376 for straight elec. So a difference of 60 this time, which is close enough to 61. The difference probably just comes from the rounding off of fractional beakers.

Ok.. So like I said, I don't really understand why I got so many beakers for electricity. Maybe there was a flaw in my test... but if the test can be trusted, then it looks like there is no beaker benefit to trying to maximise overflow on techs that the other players already have.

 

[Windsor]

Knowing physics = 20% discount.

For some techs, like paper, you get 20% if you know Civil Service and another 20% if you know theology.

 

[karadoc]

Ah. Fair enough. That sounds about right.

But on the other hand, I thought that the prereq part of the research multiplier was standardized so that it was 100% for one prereq - which would mean that the 'bonus' from physics would already be factored into the listed cost. The reason I thought that's how it worked is that I remember one time I was comparing the cost of Industrialism to Flight. Although Industrialism costs more beakers, the game was telling me that both would take the same time. No other civs had either of them. Anyway, I vaguely remember that when I just took the beaker cost and divided it by my beakers per turn, I got the right number of turns for industrialism, but less than the actual number of turns for Flight. I figured this was because flight had no "arrow" prereqs and so it was actually get a 20% penalty. So I just don't know. I think you're probably right about the 20% physics discount, but then I don't know what was going on with Industrialism and Flight. Maybe it has something to do with that game being on Epic speed and this one being Normal.

 

[icefire34]

The bonuses for overflow beakers are calculated based on the previous tech's bonuses, rather than the current tech's bonuses. In this case the overflow beakers didn't receive a bonus since Hunting doesn't have prerequisites, but if the overflow had come from a tech with prerequisites then you would get the research bonus for those applied to the overflow.

There is a little more detail here: http://www.civfanatics.com/civ4/strategy/tech_research.php

 

[karadoc]

But Hunting should have the bonus for being known by other civs, right? Unless either Hunting doesn't get that particular bonus (maybe, but I dont' know why), or the overflow works differently for the different bonuses (which seems highly unlikely); then my test should have shown the overflow bonus.

That article that you linked to. I've seen it before, but it is pretty old. It might be out of date. Actually, the person who first showed me that article was the same person who told me the beaker overflow exploit had been fixed.

I've never used the world builder before... but I'm going to have a shot at it now to set up another test.

-- edit --
Ok. Using the world builder, I set up a tiny map with no other civs. Emperor difficulty, same as last time. I gave myself all the prerequisites for writing; and I researched as close to the end of writing as I could to maximise the overflow. When I was 2 beakers away getting writing, I gave myself a few great scientists to boost the research rate. Ok. So with a research rate of 39/turn, I first researched writing and then sent the spill over to bronze working. The total on BW after two turns of research was 93. Without finishing writing first, the total was 96. I repeated the test with a research rate of 9 instead of 39. The results were 21 beakers for writing->BW, and 24 for straight BW.

By the way, I also tested that the bonus exists in the first place: 9 beakers towards writing became 14. 9 towards BW became 12. 39->56 for writing, 39->48 for BW.

I think this is pretty conclusive. The overflow uses the multiplier of the tech that the beakers are actually going towards - which is how it should be.