The purpose of the true effectiveness program is to take overkill into account and calculate how much is your attack/HP really increased by when you apply upgrades. For example a 5% increase to attack might not have any effect because it would still take the same number of shots to kill the opposing unit.
Format of input:
Resistance, Attack, HP - As appears on UI in unit stats. Eg resistance: 0.3. Only put the resistance if it is the same type as the other units attack. Eg musketeers have 0.2 melee resistance. If comparing against a skirmisher put the resistance as 0 as skirmisher damage is ranged.
Victim attack, attackers HP and resistance are not used into the calculation and may be left as 0 value. They're only important if you wish to use the SWAP function.
You may use this program to compare the effect of increasing victim HP or increasing attacker attack but not both at the same time. That would ruin the objective.
What the output means:
If you apply a 30% increase to attack and you get 21% output, it means your increase in attack upgrade is actually only as effective as a 21% one because of overkill.
Similarly if you apply a 30% increase to HP and you get 35% out it means your 30% increase is actually equivalent a 35% increase due to more overkill from your opponent. This happens because at 35% increase your opponent needs as many shots to kill you as if you had a 30% HP upgrade.
On attack mode even if you put a +ve increase you can get a negative answer! For example if you get a -10 output it means if your attack was 10% less than the base attack, you would still kill your victim unit in the same number of shots/hits as you are with the upgrade.
Why this is useful?
Pure interest and also to see the amount of villagers to wardance on the firepit. It also shows HP upgrades > attack uprades!
This information is found in the About box (by clicking the information button on the program).