>>��It is more effective to use more than one method.
>>��For example, the failure rate of the Pill in practice is thought to be
>>��around 9% per year. If you start with 100 women, then 9 would likely get
>>��pregnant.
>>��The failure rate of a condom and spermicide is thought to be around 13%,
>>��ane similarly starting with 100 women, 13 then would likely get pregnant.
>>��Now if you were to use both methods, things are much better, for example,
>>��of the the 9 that might have gotten pregnant on the pill alone, theoretically
>>��only 13%--or 1 of them--would likely get pregnant using both methods.
This is correct mathematically, but keep in mind that theory and practice do not always agree. Someone who has 'bad luck' with the pill may be a poor user of condoms for the same reason. The only numbers which really have meaning are those based on actual research studies. And while it seems reasonable that two methods are more effective than one, there are many factors to consider. Knowing that you are on the Pill may make you less careful with condoms, reducing the effectiveness of the system. Please don't forget you can still get pregnant no matter how careful you are.