## LESSWRONGLW

For someone murdered at home in the dead of night, the dominant probabilities are that either the murderer was invited in or lived there. Roommates merit investigation. If the evidence clears spouses/lovers and close family, then the probability of it being a roommate goes up considerably. Being female is not going to lower the probability enough to eschew a thorough investigation.

You're not disagreeing, but you're failing to consider the numbers here. If, say, a quarter of people are murdered by their roommates, and males are 10x more likely to be kill... (read more)

Okay, let's go with your number... let's suppose hypothetically that you aren't beating or otherwise unduly coercing cute girls into saying what you want, and you started with the probability of 2.5%. Then your suspect tells you they were at the house covering their ears not to hear the screams as their big black boss murdered the victim. Now what happens to 2.5%? After you clear the big black boss, what happens?

I don't think you can claim base rate neglect without also claiming police brutality, coercion, and leading the witness (which would be a much bigger problem)

2Epictetus5yDepends on whether murder by roommate and murder by female are independent. An average taken over the all homicides includes gang violence, robberies, bar fights, etc. Some kinds of murders are overwhelmingly perpetrated by males, while others are more balanced (for example, males are only 50% more likely to kill their children than females). Once we narrow down the circumstances of the murder, all kinds of dependencies and conditionals start popping up and the base rate becomes less relevant. Agreed. Police try to shoehorn in their theory and the press isn't going to let the truth get in the way of a good story.