Wikipedia:WikiProject Military history/Academy/Using statistics

When you find numerical information concerning actions, engagements, battles and operations, campaigns or wars, be extremely careful.

It has been a common trait as long as humanity itself, that victors in conflicts try to diminish their own strength and exaggerate that of their opponents. Also, own losses are played down while those of the opponent's are embellished.

It is always useful to verify all numbers, and ask a few questions, before entering them to the article.

Force strength
The strength of ones own force is always better known, but that of the opponent's strength is always an estimate. Political propaganda plays a role here also. Claiming a victory over the large horde or an heroic defeat to the overwhelming force is always appreciated more at home than similar outcomes between equally matched armies. (See for example Xenophon's Anabasis.)
 * Who is giving the numbers?

Very often the value of ones allies' forces are often played down. Typically they are only mentioned in passing, their strength and effectiveness are downplayed, and sometimes they are forgotten altogether. The converse applies to allies of an opponent. (See Spanish conquest of Mexico.)
 * Who are included in the numbers?

This is a very relevant question when writing about modern wars. Modern armies, navies and air forces are highly organized and specialized, and that has been used to confuse the numbers. Typically the victor counts only those troops included in the strength of the combat units and formations, and neglects to mention the support troops, while the loser's numbers include all the troops outside the combat organization, such as supply, pioneer, fortification and others. As a rule of thumb, the supporting troops are present in battles and operations with a ratio of 1.5:1 (early in the 20th century) or 2:1 later in the 20th century to the strength of combat troops. (See Continuation War, where Finnish divisional strength was around 230,000, but total number of troops under arms was 530,000.)
 * What and who are included in the numbers?

Trainer aircraft form a substantial part of every air force in the world. However, while they are not usually seen as combat types, it doesn't prevent them being added to the battle strength of the opponent's air forces. Naturally they cannot be found in the combat aircraft strength of own forces.
 * What planes are included?

It is always easy to use the strength "on paper", or what should be in any given kind of unit as a strength estimate, own or opponents. The variation of this is to count numbers assigned to the unit, regardless of how many of them are operational, i.e. in actual use by the troops in combat. (The classic example for this is the historic handling of German tank strength in the Battle of Kursk.)
 * Is it the operational strength, or a strength "on paper"?

Casualties
Again, it is far easier to count own casualties than estimate opponents. Here also domestic politics or embellishing military tradition creates problems with statistics as own casualties are minimized and opponent's maximized. (In the Winter War, Soviet initial reports were 48,000 Soviets killed and 85,000 Finns killed. With modern statistics from both sides it has been changed to 126,000 Soviets and 26,000 Finns killed.)
 * Who is giving the numbers?

Different sources use different definitions to casualties. It could mean those killed in action, those killed and captured, those killed, captured and seriously wounded, those killed, captured and wounded or those killed, captured, wounded and evacuated due to medical reasons (frostbite, accidents, non-combat related deaths, nervous breakdown etc.) Many authors fall into this trap, as they don't know what their sources include in the term "casualty".
 * How the term "casualty" is defined?