How does the trickleback modifier work?

[Centurian42]

Obviously it determines how many of your casualties are returned to your manpower pool as having just been wounded. But does anyone know the formula for how it determines this? I assume that if I change the base value in the misc.txt file from 0.15 to 0.35 then with no technology I would go from getting 15% of my manpower returned to 35%. But how is tech applied to the base value?

If I then research Early Great War Hospital System, which adds +2% to the trickleback modifier is my new trickleback modifier BaseValue + 0.02 or is it BaseValue * 1.02? Or is there some other formula? Are there any safeguards in place to guarantee that no amount of research will give me a trickleback modifier greater than 1 (there are no killed and taking casualties actually gains me more MP)?

[Nick3210]

I tested and studied this question when I needed to make a difference between USSR and Germany.

According to historicity, Germany should have had 30% in 41 returned to service, USSR 35%.

So, finally, I set 0.25 basic koeff in Misc-file.

# Trickle-back factor for manpower from losses in battle. (ie, how many are just wounded.)
0.25 # 0.3 #0.25 # 0.15 # 0.2 # 0.35 # sov 70% from 50% = 0.35 # ger 40% from 75% = 0.3

3 Techs give 5 + 5 + 5 = +15% in 1940 in my mod.
0.25 + 15% = 0.29 coefficient , OK, that's what I wanted for all countries in 1940.

For Soviet military medicine I add additional event:

command = { type = trickleback_mod value = 20 } # +20% to 0.25 = 0.3 , plus 15% techs = 0.34 in 1940 for Sov, Ger = 0.29 in 1940

[Centurian42]

Originally posted by Nick3210:

According to historicity, Germany should have had 30% in 41 returned to service, USSR 35%.

That's interesting. I wasn't sure where to find specifically how many casualties were returned to service, so I went by the raw ratio of wounded / (wounded + killed), which will generally be somewhere around 0.6 or 0.7 for most conflicts*.I was a bit timid about setting the base trickleback factor that high since I don't want to risk maxed out tech resulting in a trickleback factor greater than 1 (I am playing NWO2 so there is a full century's worth of medical advancements to worry about). As such I went with a base value of 0.35.

But if you came across information specifically about how many soldiers were returned to service, not just how many were wounded, then I might follow your example and set the base value to 0.25.

*One interesting thing I noticed is that the proportion of wounded out of wounded+killed for a given nation was actually higher in WW1 than WW2 (for Germany 0.67 in WW1 and 0.58-0.62 in WW2). Suggesting that perhaps the nature of the fighting has more to do with numbers of wounded than medical technology alone (although technology must start to make a difference at some point). Just an interesting sidenote that threw a wrench in my plans to adjust the medical research to reflect historical improvements.

[Nick3210]

The Trickle-back coefficient in the game mechanics works as "returned to service" / wounded+killed.
So number of those who "returned to service" do not include crippled survivors and those who died in hospitals. This is the reason why real coefficient can't be 60-70%.

Therefore, in order to set the most realistic parameters in the game, we must find two statistical ratios for each of countries.

1. The Ratio of dead and wounded
2. The Ratio of those who returned to service to the total number of wounded (from point 1.)

According to information that I was able to find (russian-language WW2 resources), for the USSR and Germany these parameters approximately look like:

USSR - 70% (!) returned to service from 50% of all losses = 0.35
GER - 40% returned to service from 75% of all losses = 0.3

(May be I really used too optimistic ratio for Ger 75%... not 60% - can you give any links for 0.6 Ratio for Germany? In this case the result for Germany will be much worse 40% of 0.6 = 0.24 )

These data clearly show the fundamental difference in organization and strategy of military field medicine of USSR and Germany.
Germany tried to evacuate from the battlefield and tried to save all the wounded.
USSR tried to evacuate from the battlefield and tried to save only those who had a chance to survive.
May be the soviet strategy was more cynical, but as we see it is more effective.

hm... I immediately remember Covid and the crowded hospitals in Spain and Italy which decide who to give a chance to survive, and who to leave behind the doors of the hospital.
That's military field medicine style, yes.

http://images.vfl.ru/ii/1593647626/65057b82/30964740.bmp

[Centurian42]

Yeah, it was that last step I was missing, the ratio of wounded returned to service out of total wounded. Do you know a good source that lists this value for various countries over various conflicts? That might be interesting to peruse sometime. Where did you find 40% for Germany and 70% for USSR?

As for just getting wounded out of wounded+killed I used the Wikipedia numbers for German killed and wounded in WW1 and WW2, as I'm not sure where to find better sourced numbers.

For Germany in WW1 (according to Wikipedia): 4,215,662 wounded / (4,215,662 wounded + 2,037,000 killed) = 0.6742

https://en.wikipedia.org/wiki/World_War_I_casualties#:~:text=The%20total%20number%20of%20military,deadliest%20conflicts%20in%20human%20history.

For Germany in WW2: 7,300,000 wounded / (7,300,000 wounded + 4,440,000-5,318,000 killed) = 0.5785-0.6218

https://en.wikipedia.org/wiki/World_War_II_casualties#:~:text=World%20War%20II%20was%20the,country%20count%20of%20human%20losses.

[Nick3210]

I do not think that somewhere there is accumulated information for all countries.

In all Russian-language resources for the USSR the figure of 70-75% of those who returned to service is used.
49% in catastrophic 1941
75% since 1942.

I don't know where these numbers were originally taken from, but they are used everywhere in russian-language resources, so I don't have any other numbers besides these.

http://images.vfl.ru/ii/1593692560/9927e4f0/30968967.bmp
https://proza.ru/2015/12/05/1247

Effectiveness of German military medicine in Russian-language resources is estimated as 40-45% returned to service.
"...The increase in the number of irretrievable losses of the German army was facilitated by the fact that the German sanitary service, based on the experience of fighting in Poland, France, Yugoslavia, and Greece, did not take into account such important factor as the stretched communications.
Before the war with the Soviet Union, the Germans provided good mass reception of the wounded and sick, their evacuation to the rear and treatment in specialized hospitals, since the separation of the active army from the main mass of hospitals was small.
But then the situation changed abruptly. The German army was separated from its hospital bases at a much greater distance. In such situation, a well-organized front-line sanitary service with large evacuation apparatus and powerful triage hospitals is necessary. The German health service has none of this..."

But I would be interested to know the German assessment, but without knowledge of the language, it is difficult for me to find such information.

[Centurian42]

Ok, here's what I've done. I need the base value + the first few techs to be a reasonable trickleback value for WW1, and I need the max value (base value + maxed out tech tree) to be less than 1, and ideally some value that is reasonable for early 21st century battlefield medicine (don't know how high this value should be, but in the recent conflicts in Iraq and Afghanistan the US suffered ~10 times as many wounded as killed, so if wounded comprise about 0.9 of casualties then returned to service I'm guessing is probably not higher than 0.8). I also want the trickleback mod for WW2 (base value + all techs prior to 1945) to be a reasonable value for WW2 medicine.

Since I'm playing NWO2 I need the tech tree to do a reasonable job of modeling the trickleback over a full century's worth of improvements. The default buffs to trickleback result in a value greater than 1 when the tech tree is maxed out (1.08 + the base), which is clearly too high.

I've set the base value to 0.3 (a bit low for WW1). And I have cut each tech's tricklebad mod in half (Early Antibiotics has a trickleback mod of 0.5 now instead of 1). This means that at the beginning of the 1914 scenario Germany has a trickleback modifier of 31.5% (lower than it should be, but within reason), at the beginning of the 1941 scenario the Soviet Union has a trickleback modifier of 36% (about what it should be), and at the beginning of the 1980 scenario the US has a trickleback modifier of 67% (no idea what it should be, but this doesn't seem too unreasonable). With everything maxed out the value should come out to 84%, which is a bit higher than I aimed for but not by much.

If you know where to find the proportion of wounded in Vietnam who were returned to service then I could check to see how close the value at the beginning of the 1972 scenario is to what it should be.

[Nick3210]

I have digged in this question more..
I found data of the ratio of losses in the Wehrmacht in 39-40. (Tippelskirch)

War in Poland:

- 11 thousand killed;
- 30 thousand wounded;
- 3 thousand missing persons.

War in France:

- 27 thousand killed;
- 111 thousand wounded;
- 18 thousand missing persons.

Obviously, the dead and missing must must be summed up.
Therefore, for fast victorious blitzkriegs of 39-40, we have indicators of 0.68-0.71 wounded.

I also found estimates based on the results of the entire WW2 for countries (Urlanis)

First world war:

Germany 2.9
US 4.2
France 3.3
UK 3.5

World war II:

Germany 1.34
USA 3
France 1.67
United Kingdom 1.34
Belgium 1.25
Italy 2
Poland 2

So, Germany totally for all WW2 have 1.34/ (1 + 1.34) = 0.57 (better in 39-40, worse in 41-44)

Also, I found out that the autumn and winter of 1941-42 turned out to be a disaster for the rate of return of the wounded to service. (Stretched communications, large distances from the home hospital network, and additional mass frostbites of wounded).
Therefore, I will have to make a special event from October-41 to April-42, which will reduce the trickle back factor for Germany.

Now, new, rebalanced trickle back factor in my Mod looks:

0.25 (basic in 1918) + 20% (for techs) = 0.3 in 1940
+10% in 1942 = 0.325
+20% (penicillin) in 1944 = 0.375

USSR get additional +30% bonus since 1942. (0.42 in 1942)
http://images.vfl.ru/ii/1594559328/5585c0d3/31056921.bmp