What, exactly, do the percentages mean?
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What, exactly, do the percentages mean?
| Wed, 03-10-2004 - 11:40pm |
We are all familiar with the percentage effectiveness of all of the forms of bc we use. But, I was wondering recently, what do they mean really? For instance, if the pill is 99% effective, does that mean that one will become pregnant in one out of 100 sex acts? (I know it couldn't mean that, I was just making an example.) What exactly do those numbers refer to?
Express!
Beth "Petrouchka"
Signatures On
| Thu, 03-11-2004 - 12:13am |
It means that in a study of a group of 100 women, taking the BC over a period of time (usually a year I think) 1 woman got pregnant. If it says 99.9% or some other decimal, it probably means that out of, say, 1000 women, less than 10 got pregnant. Hope this helps:)
| Thu, 03-11-2004 - 12:29pm |
A couple of other things to look at. Usually the studies are done in the first year of use. Some studies have shown that effectiveness increases with time, probably as a result of people getting better at following directions! Also, look at whether an effectiveness rate is "ideal" or "typical" (also called "expected") use. Idea use is determined from very controlled groups, who used the method *exactly* as prescribed, *every* time. Typical or expected use is determined from a sample that is monitored in the "real world" so to speak, where some people are very diligent, and some aren't.
