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HIV Vaccine!

fls said:
less than 4% confident that the results represent a true-positive.

Linda
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Now I see what your problem is, we are arguing two entirely different things. I am not saying anything as to how likely the results are true positive, I am arguing that there is a high confidence that when taking a survey of the population, you are likely to obtain the results that were found in the study.

WHAT I MEAN IS.........

Go out and pick 8000 random people in the area that the study was conducted. There is a likelihood that the range of people that contract aids in 3 years contains the results found in the study, so there is a possibility that your hand picked results could be 51 people. WITHOUT ANY DRUGS BEING USED ON THEM!
 
Lothian said:
It is easier for people to decide by reviewing the absolute than the relative risks.
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This may well be true in some cases, but you have to be careful that you present them in the correct way. If you had said "The chance increased from 1% to 1.24%" I wouldn't complain, but it's simply not true to say it's an increase of 0.24%. Trying to avoid confusion by stating things in an even more misleading way does not help matters.

Careyp74 said:
I don't like when stats are used like that. If the numbers were slightly different, say, 51/8000 and 102/8000 instead of 74, you could say you have a 100% greater chance of getting HIV without the treatment. That sounds drastic when it isn't at all.
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Personally I'd consider a 50% less chance of catching HIV reasonably drastic, especially when there is essentially no risk or inconvenience involved.
 
Careyp74 said:
When figuring out the confidence interval of expected results based on, say, 95% confidence (doesn't matter but let's just use that level) you are going to use the same numbers from my example as in yours. n is not 1, it is 8216. It doesn't matter that it is one person doing the test, just like it doesn't matter if it is one person that flips a coin 10 times, or 10 people flipping a coin once each.
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It all depends upon what question you are asking. We are not really interested in the probability distribution of outcomes if an individual were to receive the vaccine over and over and over again. We are interested in the distribution for the population. In one case, you are describing repeated measures on an individual, which tells you only about that individual and cannot be generalized to anyone else. In the other case you are describing repeated measures on a population which tells you about the population and can be generalized to other members of that population.

Linda
 
Careyp74 said:
Now I see what your problem is, we are arguing two entirely different things. I am not saying anything as to how likely the results are true positive, I am arguing that there is a high confidence that when taking a survey of the population, you are likely to obtain the results that were found in the study.

WHAT I MEAN IS.........

Go out and pick 8000 random people in the area that the study was conducted. There is a likelihood that the range of people that contract aids in 3 years contains the results found in the study, so there is a possibility that your hand picked results could be 51 people. WITHOUT ANY DRUGS BEING USED ON THEM!
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I realize that is what you are referring to. The problems are that it is an incomplete answer to the question, and that you made a mistake when performing the calculation, as the likelihood that sampling again would lead to a sample with 51 people with HIV is less than 2.5%. It is an incomplete answer to the question, as it simply tells you the probability that you would get this result if all you were using was chance. But that's not what you want to know. What you really want to know is, when I obtain this particular result, what is the probability that I obtained it because of chance or because of something else that I was using?

Linda
 
Puppycow said:
.2875% doesn't sound like much for an individual but .2875% of 1 billion people is 2,875,000.
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No, there is no guarantee that the difference is going to be multiplied out for the population, and it is quite possible that with the who population we could see a result that is worse than the placebos, because they are so close. that is the whole argument occurring in this second page of the thread.

Think of it like flipping a coin (please Linda I know what you are going to say, this is just in reply to Puppycow's quote) if you flip heads 20 out of 50 times, will that mean that you will flip heads 40 out of a hundred?
 
Careyp74 said:
No, there is no guarantee that the difference is going to be multiplied out for the population, and it is quite possible that with the who population we could see a result that is worse than the placebos, because they are so close. that is the whole argument occurring in this second page of the thread.
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Except that they are not very close. In fact, they are so far apart that the probability that a difference this large would occur, simply due to natural variation, is less than 2.5%.

Think of it like flipping a coin (please Linda I know what you are going to say, this is just in reply to Puppycow's quote) if you flip heads 20 out of 50 times, will that mean that you will flip heads 40 out of a hundred?
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If you have a biased coin, that is what it means.

Linda
 
LostAngeles said:
It's a breakthrough. The two vaccines used were ineffective in earlier trials on their own. This one combined the two.
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Listening to a prof at Imperial College London on the radio he suggested that the results are not impressive enough for this to be licensed as a treatment. However it is nevertheless encouraging. Given the previous failures of the individual drug this result was a bit of a surprise. If we can work out why it worked we should be able to develop much better vaccines very quickly.

Fingers crossed.
 
Update:

'Mosaic' HIV Vaccine Announced - Trial to Launch in 2012

Today Los Alamos National Laboratory (LANL) announced a "mosaic" HIV vaccine designed by HIV geneticist Bette Korber. An international team of investigators has entered the final testing stage before beginning a human clinical trial. The Phase-I Clinical trial, to be funded by Bill & Melinda Gates Foundation and the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, would launch by late 2012.
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