Collecting data on violence against women is fraught with challenges. Dr Henriette Jansen, UNFPA's lead researcher on VAW data and the technical lead of the kNOwVAWdata initiative, lists six key rules for success.

Excerpt:

All of us working in this field know that violence against women (VAW), in particular intimate partner violence, affects women across the globe, regardless of which country they live in or their socio-economic status.

It is also generally known that collecting quality and reliable data on VAW through special surveys is crucial if we want to understand and end this scourge.

But collecting accurate data is also very challenging because surveys, regardless of how well the method and tools are designed, do not measure the actual number of women who have been abused, but rather the number of women who are willing and able to disclose abuse.

And surveys always do miss the most severe cases; including those institutionalized, locked up, too scared to talk - or murdered.

Read the full piece at the Sexual Violence Research Initiative website: http://www.svri.org/blog/six-golden-principles-interviewing-women-who-may-have-experienced-violence