Expert/company advocating this approach (if applicable):
Fisher Price

Description of method:
A small battery powered alarm with sensors is attached to the child's underwear. If a sensor begins to get damp, the alarm goes off, waking the child who will hopefully rise and go to the bathroom.

Recommended age for this method:
I used this when my third son was nearly 4. My friend used it when her children were 5.

How long should it take for child to be potty trained by this method?
This is really for night training. We had success in about 4 weeks.