Method of assigning white/black?

Does anyone know of an official link where it explains how the site assigns sides? Is it truly 50/50 each game, or are there other factors at play?

I read an explanation the other day by one of the mods (Martin_Stahl, I think), so I'll try and explain it the same way.  It's random, but the site tries to keep an overall balance of 50/50 if a player is getting more of one color.  It can get slightly more out of balance though if 2 players are matched who are both getting more of black.  Hope that helps...

 

This says it is random: https://support.chess.com/article/1304-how-can-i-choose-my-color

 

But I'm pretty sure I've seen post from staff in the past that stated that it is influenced by overall balance, but it is possible my recollection is incorrect or it has changed.

I guess it could be simultaneously random AND influenced by past numbers. For example, if Player A is paired with Player B, and Player A has played a higher percentage of games as white than Player B, then the sides may be randomly assigned with the odds of Player A getting assigned White being something like 45:55 instead of 50:50.

The phrasing in the above linked article seems a bit ambiguous in what the writer means by random, since an event can be random without having 50:50 odds. My gut tells me the writer meant to imply 50:50 odds, but mathematically speaking, it is not clear.

Would anybody who is “in the know” care to chime in? In any given random assignment of sides to players in a game, are the odds always 50:50? Or are the odds modified based on past percentages of white/black for the two players?

I asked a friend that's on the QA team and he said it was 100% random but if you have played the person before it assigns the opposite color to the last time.