Posted on 02/14/2003 9:12:00 AM PST by fight_truth_decay
Before you go.....if you have a better understanding of person years will you post it before you leave? Thanks.The "person years" is obscure to me as well, but I'll look at it again over the weekend. I also find it as difficult to believe as you do that the incidence of HIV transmission without a condom is less than 7%.
Have a good one, RP.
"Never" using condoms is ~93% effective, "always" using condoms is ~99% effective, therefore "always" is 85% MORE effective than "never."The major and minor premises of the above-stated syllogism are both false.
Major Premise: Never using condoms is never effective, as can be demonstrated by a simple syllogism:
Every effect has a cause;To say that "never" using condoms is 93% effective is like saying that condoms are 93% effective when not used, which is absurd. As the poster in #6 above correctly pointed out, condoms are 0% effective when not used.
Inaction is not a cause;
Therefore, inaction has no effect.
Minor Premise: The effectiveness of a prophylactic is calculated by (a) subtracting the total number of unfavorable events that occur in the group using the prophylactic from the total number of unfavorable events that occur in the control group (i.e., the group not using the prophylactic, and (b) dividing the difference by the total number of unfavorable events that occur in the control group. For example, if we wanted to know how effective seat belts were in preventing traffic fatalities and we knew that 7 of 100 motorists who never wore seatbelts were killed in traffic accidents but only 1 of 100 motorists who always wore seatbelts were killed, we would subtract 1 from 7 and divide the difference by 7, giving us an effective rate of .85, or 85%.
The data in our example do not support the onclusion that seatbelts are 99% effective. To determine the effectiveness, we have to compare the results of the test group to the results of the control group. Comparing the actual number of traffic deaths in the test group (1) with the total number of motorists in the test group (100) doesn't tell us how effective seatbelts are, only the chances of surviving a traffic accident while wearing a seatbelt -- that is, 99 out of 100 times, or 99%.
The data support Bozell's conclusion that condoms fail to prevent HIV transmission 15% of the time . Condoms are 85% effective against HIV transmission, not 99%.
Maybe these were couples who found themselves in the situation of one partner being infected and one not. Yet, that would mean either someone had a blood transfusion, is an IV drug user, or has not been monogamous. There would be study problems with some of those?
I haven't read the study, just its conclusions. I didn't want to download the whole thing. Maybe I will later if I have time.
You're kinda missing the point.Your point was that Bozell is distorting the test data, and he is not.
Less than one chance in a hundred over a hundred years. That is NOT "85%."One chance in a hundred hundred over a hundred years v. 7 chances in a hundred over a hundred years is 7 minus 1, which is 6, divided by seven, which yields an 85% effectiveness against transmission.
No, Madg, I think that's PER YEAR. It is not possible that they mean to stretch the risk ratio out over 100 years. Most people don't even live that long. It is just a way of calculating your risk over time. I think this study says you have approx. a one percent chance PER YEAR of getting the disease. If your years of risk increases, then your total risk increases.
I'll get back to you when I have time to find the facts on time versus risk factor.
Correct and consistent condom use is a HECK of a lot better than 85%.The NIH data don't support such a statement, so your beef is with the accuracy of the NIH data, not with Bozell's interpretation. Assuming the accuracy of the NIH data, Bozell correctly states that condoms failed to prevent HIV transmission 15% of the time. There's nothing even remotely deceptive about that.
A 1% transmission rate in the "always" group tells us that the risk of transmitting HIV in that group is 1%. A 7% transmission rate in the "never" group tells us that the risk of transmitting HIV in that group is 7%. Neither group by itself can tell us anything about the effectiveness of condoms. One can only assess the effectiveness of a condom by comparing the number of transmissions in the "always" group with the number of transmissions in the "never" group. Assuming the accuracy of the NIH data, condoms were only effective 85% of the time.
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