This survey is a case in point. Women can READ the data (the surveys are posted here) but still not fully appreciate how the information revealed in the survey could have a profound impact on their behavior.
If you are a sexually active woman that should make you stop and think. Just those two responses tell you, there is a 50/50 chance that your new prospective partner will lie about the number of partners he's had, and no matter what he SAYS, he has no idea if he is infected or not (most STDs are asymptomatic especially in males.)
But when sexually active adults are asked if they are concerned about getting infected, they say, "No. I think I would be able to tell if someone is infected." Or, "I asked my partner to get tested before we had sex." Or, "I've been with this partner for awhile now, so I don't really worry about it."
It's obvious they haven't processed ANY of the relevant information regarding annual STI in their age group (it's one out of every TWO new infections!)
OK, let me see if I can take a stab at making this REAL.
YOU will NOT be able to tell if someone is infected. Your partner may not tell the truth about the sexual risks they have taken (number of partners, if they've paid for sex, etc.) Your partner may not KNOW that they are infected (or they may avoid telling you).
The most common sexually transmitted infection (HPV) can live UNDETECTED in the human body for years. Some STDs (HPV, Herpes, Syphilis) can all be passed by CONTACT with infected skin not covered by a condom.
If you actually process what you just read, you should conclude that you have taken greater sexual risks than you realize!