A commonly spread statistic regarding custody is that men are more likely to win if they fight for it. I want to talk about this in two parts: survivorship bias, and the problematic corollary.

Survivorship Bias

Survivorship Bias is a commonly committed error in the analysis of data where one attempts to understand the reasons for success/failure of an event by analysing only the successes. The most famous example is where planes coming back from war were full of bullet holes basically everywhere but the engines - the mistake is made where one sees this and adds protection everywhere but the engines, neglecting the fact that the engines are just as likely to be hit as everywhere else but those planes did not return.

The way this bias takes hold in custody analysis is subtle and often overlooked. By stating that men are more likely to win if they fight the custody battle, you are committing suvivorship bias because your pool consists almost entirely of men who had the means to fight an expensive and time-consuming battle, and whose lawyer told them that they could win, in the first place.

To draw the similarity to the plane example, the "survivors" are those with the means to fight the custody battle. Having the means (ie, financial stability and time to spare) increases your chances of success, so by looking only at those who have the means in the first place, you are biasing your sample. You are not looking at those who do not have to means to pay for a hefty court battle.

In most of these cases, the woman does not have the means to fight a court battle any more than the man, but is more often successful anyway because they are the assumed victor and custody recipient until a court rules otherwise.

We should not be overlooking those who did not fight. We should be asking why women are the assumed recipient, while men have to spend tens of thousands to even have a chance.

The problematic corollary

The corollary to the statement "men are more likely to win if they fight for it" is that those men who didn't fight for it would also have had a better chance of winning had they fought. Assuming there would no bias, this would have been a fair argument to make, but the conclusion is absolutely biased, which means that this corollary is not necessarily true. Based on the data as a whole, I'd argue it is false.

It is problematic because it diminishes the fight for equal custody rights. It implies that men already have equal rights to custody when they simply don't - those that get custody have to pay tens of thousands, while women get away with paying much less. It implies that if a man you know doesn't have custody, likelihood is that he didn't deserve or want it. It encourages the "deadbeat dad" trope, while women are treated with care and understanding.

Conclusion

The statistic used to justify the statement that men are likely to get custody if they fight for it is based on a biased analysis of the data and leads to problematic conclusions in which men's issues are overlooked, and can lead to the demonisation of individual men. The courts are heavily biased towards women, not only giving them better chances and assumed victory but requiring men to cash up tens of thousands for even a hope of 50/50 - assuming the mother doesn't sabotage this after the hearing.

The best predictor of whether or not you will get custody is not whether you fight for it - it is whether you have the means to do so. And if that is not expected as a bare minimum of women, it should not be of men.