positive efblfect or decrease i mortality had flaws in them and the world health organization and american cancer society actually agree that, for instance, the canadian study had a lot of flaws, they used very old equipment, they had technologists and radiologists that weren't qualified or trained well, and when that study was done in the '80s, they just weren't using state of art mammography at the time. >> so the study brings into, obviously, these major questions. we know that mammograms save lives. you cannot say that enough. we know that at this point, but these researchers say the harm of mammograms in that these false positives is a real concern. is that not valid? >> no, i think that is valid. there are some false positives. approximately one in ten women who come in for a screening exam may be called back, and that's called a false positive, to get further imaging to see if what