They say that only one in four rapes are reported. How do they know?

Question: They say that only one in four rapes are reported. How do they know?
- Keywords:
  illegal,
  law,
  rape,
  reported,
  society,
  statistic
Asked by 1drawsome to Cathal, Daphne, Darren, Jon, Katherine on 16 Mar 2012.
- Katherine Haxton answered on 16 Mar 2012:
  
  Someone probably did a study where they asked people to say if they had been raped, and if they had reported it to the police. It’s quite a worrying statistic, and it’s also quite worrying that a lot of those crimes that are reported don’t end up with someone being arrested for it. People need a better way of dealing with crimes like rape because its so traumatic for the victim.

Question: They say that only one in four rapes are reported. How do they know?