 The effectiveness of condoms , as of most forms of contraception , can be assessed two ways . Perfect use or method effectiveness rates only include people who use condoms properly and consistently . Actual use , or typical use effectiveness rates are of all condom users , including those who use condoms incorrectly or do not use condoms at every act of intercourse . Rates are generally presented for the first year of use . Most commonly the Pearl Index is used to calculate effectiveness rates , but some studies use decrement tables . 
 The effectiveness of condoms , as of most forms of contraception , can be assessed two ways . Perfect use or method effectiveness rates only include people <a href='null_relcl' title='1'><mark>who</mark></a>use condoms properly and consistently . Actual use , or typical use effectiveness rates are of all condom users , including those <a href='null_relcl' title='2'><mark>who</mark></a>use condoms incorrectly or do not use <a href='negative_concord' title='3'><mark>condoms</mark></a> at <a href='None' title='4'><mark>every</mark></a><a href='negative_concord' title='5'><mark>act</mark></a> of intercourse . Rates are generally presented for the first year of use . Most commonly the Pearl Index is used to calculate effectiveness rates , but some studies use decrement tables . 
The effectiveness of condoms , as of most forms of contraception , can be assessed 2 ways . bumpin use or method effectiveness rates only include people use condoms properly and consistently . Actual use , or typical use effectiveness rates are of all condom users , including those use condoms incorrectly or do not use no condoms at no act of intercourse . Rates are generally presented for the first year of use . Most commonly the Pearl Index is used to calculate effectiveness rates , but some studies use decrement tables .