Why are women not as successful as men in chess?

"You can deduce, or assume, from a valid pool, but can't compare from a smaller and a larger pool"

Of course you can compare, as long as the smaller pool is large enough, it's quite alright that it's much smaller than the larger pool. As long as each pool is large enough that you can pinpoint its tendencies, then it's fine. That's why random samples can work for talking about large populations, even if the sample is a tiny fraction of that population. Early on, the size of a sample makes a big difference in accuracy, but once the sample gets to a certain size, any increases in size will have a negligible impact on accuracy.

"How many of them play actively in tournaments? From all the women I've seen reaching good level and titles, only one remains truly active: WGM Deisy Cori. Out of +20 in the past 20 years in Peru."

Well I would assume at least hundreds or thousands. You believe there is only one?

"For example, in western countries boys may have a hard time when joining a chess club, but girls have a nightmare when doing the same. Which may explain why China is so strong these past years."

That's a social explanation, not a statistical one. You are proposing that women get certain results because of certain social factors. That's a social explanation. I wasn't objecting to social explanations, just to the typical statistical explanation that claims that women's results are just as good as the men's when you factor in statistics. I don't know if that's what you were getting at, but I assumed you were because you mentioned very early on the "statistics" that more men played than women. You seemed to suggest that the fact that the female pool is smaller than the male pool was significant.

"When I meant: Women's pool isn't large enough to assume anything when compared to men's pool."

Ok. I would disagree with that. But I think we even disagree on the size of the women's pool. Admittedly I just assumed that out of the whole world, there are thousands of female tournament chess players, but I haven't looked it up, or at least don't remember the numbers. Would thousands of players be a large enough pool for you?

But yeah. I was mainly just responding to your statistical points. Personally, I think that there are lots of social factors going on, but it's also plausible to suggest that brain chemistry would affect results as well. It just makes sense. Brain chemistry can affect things, that's pretty logical. Do we know for sure, no, but it's plausible to suggest that brain chemistry at least plays a role, and that it's not a complete coincidence that those with different brain chemistries are getting extremely different aggregate results. We're ok with reasoning that way when it comes to non-political things, but if it's about men or women, suddenly, we change our scientific standards.

I do think that social factors intensify the disparity. More men succeed, makes more men cocky, makes women less confident, which leads to more men succeeding, which leads to more cockiness, and even less confidence for women, etc, in a feedback loop. But that doesn't mean social factors are the only thing at play, just that they are a part of it. It's like how introverts seem rarer than they actually are. One source said 1 in 3 people are introverts, but it seems like less because a lot of people either pretend not to be, or introverts are just harder to notice. So part of our perception of there being more extroverts than introverts is due to social factors, but part of it is also due to there actually being more extroverts than introverts. It's silly, to me, to just decide, it's 100% social or 100% biological, when both factors are clearly capable of having an effect.

"But then you'd have to provide studies to back you up, otherwise it's your opinion"

For the record, studies have been done suggesting that women play worse when they are told that men play better than women, or some kind of priming like that. The group of women that wasn't told that performed better than the group of women that was. They played against male players. I may be getting some details of the study wrong but you get the idea.

I think with these kinds of psychological studies you have to be tentative because you can never isolate all of the variables, but in general these sorts of studies (among other things) convince me that social factors play a role. However, how much, is quite hard to say.

@JMurakami: What I meant with chess not being an objective game is that the game might be played best by a player having a similar attitude and way of thinking like the designers of the game. It might be a game in which men have an advantage, because their way of thinking is more in line with the nature of the game. Just as you were wondering yourself when playing against women.

Retreating a piece unmanly? I have never thought that way. I just try to look at the best move, whatever it may be. In my last played game I retreated one of my pieces on the moves 24, 26 and 28, see https://www.chess.com/daily/game/150722676?page=1.

They (wemen) are women, they are beautiful when they are gracious, and graciously successful not in chess than men are.... Well... men are more strong thinkers when their minds develop and mature. Chess helps men more than women.

And, honestly, he was the same guy who stated that I "don't represent the human race" when I said that another game he posted was merely good, not excellent like he would have hoped. What did he then do next when I confronted his behavior? Blocked me, of course. ^-^

The more he stirs the pot, the more cooked he becomes.

Now, why he chose to post in a thread that is completely irrelevant to his own topic is not within my grasp, but whatever suits him, I guess. If a moderator comes, his post might be expelled from here. That's not up to me.

To simplify my point, I am not saying that "a 2000 rated female is less aggressive than a 2000 rated male."  I am saying that 'overall' in the game of chess, women digest the information much more differently than men.  So that in the end, a woman is much less likely to develop the same style of gameplay that a man will create, if they are working with the same chess data.  A man is MUCH more prone to develop an aggressive, attacking style.  Whereas a woman will likely develop a different approach(usually a more defensive, drawish style).

Defensive styles are not necessarily a bad approach, but a chess player that forms a style where they do not capture many pieces, they set up congested positions, and sorta 'wait around', this type of technique isn't gonna add up(over years of learning) to as much 'power' as a player that thinks of 'the attack' right from the first few moves(and I am not talking about attacking just the king, I mean attacking the board first, and also the king later).

Ivanchuk is a dangerous opponent for Carlsen - and for world champions in general. It wasn't the first time, and probably isn't the last one either. 

Wait, I thought I made it clear that my personal observations, and opinionated conclusions were undeniable, simply because I am OBVIOUSLY a scientist.
 

I do think however, that a little common sense thinking goes A LONG way.  I have no real emotional attachment to women being better at chess than men, or not.
I am only human, but this particular subject does not rile any emotions in me.  I may be fairly barbaric, but I am at least confident enough in myself(as a man), that I do not need to try and belittle women in ANY WAY when it comes to chess.
Men are stronger chess players than women(overall), and the reality is, the strongest chess players(in any class) are players who focus more on being confident, aggressive attackers. 

Well, let me get a little weird(not IMO, but this may sound a lil F'd up).  First, I've been playing chess since the 1900's, a game I play mostly for fun(and love of the beauty of chess pieces, artistic nature, and the timelessness of it all). Most of my chess experiences have always been with just town locals, playing chess more for kicks, and such vs clubbing up, and trying to become a master.
So, even in these sorta chess experiences that I have been in hundreds of times(playing or watching), you will notice that with 2 male players of similar strength, and experience, the more effeminate male will play more submissively, and the more egocentric cocky player will usually get MANY early attacking advantages.

It is just sorta the way the world turns.  Chess definitely reflects our personalities almost perfectly.  Sum up a person's personality, and you can almost sum up how they will play chess.  This reality of chess is one of my favorite parts of the game.  Of course a player can be trained to go against his nature.  The hardest thing a boxer has to learn is how to defy his nature to avoid a punch coming his way, a boxer has to train to 'step into' the opponent's punch(an impressive accomplishment at any level of the sport).  But at the end of a chess player's career, most of their understanding of attacking will be HEAVILY effected by the natural aggressiveness of their personality.  (I am not talking about players that are 2000+ FIDE, players at that strength and up are masters, and see the game from a whole different perspective, one I will never be able to grasp)  ): 

I am an amature chess student, and I find great comfort in Silman's philosophies(a characteristic many 2000+ players would highly disagree with).   But one of his philosophies blew my mind from the first time I heard it, and I do not know if I have ever really been able to accept his belief.  This philosophy is a lifelong goal of mine to master.  I will paraphrase him for simplicity.  "...chess is a game that is 100% won and lost psychologically, believe in yourself and win, doubt yourself and lose..."

Obviously, I do not think he means that a 1200 rated player can destroy a 2300 rated player with NOTHING more than a "tough unbreakable confidence".  But at matched skill levels, being 'mentally tough' is the key to winning(so he claims undoubtedly).  I mean, I hate to sound like I sound, but the truth is, women do tend to doubt themselves, and fall into submissive mindsets MUCH more naturally than men.

Nothing to be proud of in real life, being a cocky jerk of a man.  But we must fully understand, that cockiness, and arrogance can easily be mistaken for actual true confidence.

See?

Already, I'm not liking where this is going.

I realize that members like BigKingBud can have a quite intelligent discussion on this subject matter and still be civil/polite about it, but you see what I mean?

Let's hope this that I'm quoting doesn't progress.

At a man's core there is a primal being who spent MILLIONS of years hunting down, 'attacking', and killing food.
At a woman's core there is a primal being who spent these same years nesting, breeding and nurturing.
Both COMPLETELY equal functions for the survival of humanity.

There are always grey areas, but 'in general' men are just MUCH more naturally 'confident' in their ability to hunt down, attack and kill their prey.  IMO this shines through HEAVILY in the two sex's interpretations of how to approach the game of chess. 

Humans have been carnivores for at least 2.5 million years.  Human newborns have the longest nurturing needs of all living creatures.  Women were not hunters, ever.  They have always been nesters, even in today's world.
A woman is pregnant for 40 weeks, the further they go into the process the less 'physically capable' they become, then(after birth) they have to spend MONTHS, even years nurturing the child into self-capability.

My conclusions are not scientific(ha obviously), they are just my opinions, but my opinions are based on facts. 

http://news.nationalgeographic.com/news/2005/02/0218_050218_human_diet.html

A Quote from the article... "...Carnivorous humans go back a long way. Stone tools for butchering meat, and animal bones with corresponding cut marks on them, first appear in the fossil record about 2.5 million years ago..."