[ChrisLincoln]

So, i'm not a maths genius. But.

If a condom is 99.9% effective.

And.

The pill is 99.9% effective.


Then using both is still only 99.9% effective? So unless you have a habit of not taking your pill or breaking condoms (human error). Then using both is stupid? Or is my maths wrong and somehow using both is 198.8% effective?

[tinktinktinkerbell]

it wouldnt be stupid using both, if one failed then you have the back up of the other

[ChrisLincoln]

Originally Posted by tinktinktinkerbell

it wouldnt be stupid using both, if one failed then you have the back up of the other

But the chance of it failing and them both failing is the same - according to maths. Which again i need assurance of by some TSR maths geek.

[Bismarck]

Your math is wrong. It would only be correct if you also misused both of them at the same time. Assuming a normal distribution, the odds of the condom not working when the pill fails is about 0.1%. The same is true in reverse. The odds of them both failing simultaneously are 0.1%*0.1% = 0.021%.

[nolongerhearthemusic]

Neither are that effective. Where the hell did you get those numbers?

But yeah they are extremely effective when combined and used perfectly.

[Kater Murr]

You're not finding an average.

You multiply the reliability of the condom by the reliability of the pill (by the chance of getting pregnant without either)?

[ChrisLincoln]

Originally Posted by Bismarck

Your math is wrong. It would only be correct if you also misused both of them at the same time. Assuming a normal distribution, the odds of the condom not working when the pill fails is about 0.1%. The same is true in reverse. The odds of them both failing simultaneously are 0.1%*0.1% = 0.021%.

Ahh i see . Thanks! Thread over .

[tinktinktinkerbell]

ok just say you use both and have sex

you get a upset stomach = pill failing but you have the condom to fall back on

just say you use just the pill again you get a upset stomach = pill fail but this time it would = pregnancy

[Noble.]

Originally Posted by ChrisLincoln

But the chance of it failing and them both failing is the same - according to maths. Which again i need assurance of by some TSR maths geek.

No, if the effectiveness of the pill and condoms are both 99.99%, the probability of them both failing is 0.0001%, as opposed to 0.01% by themselves.