How is the precision of a single trial reported and how is the precision of multiple trials reported?

Answer 1

The precision of a single clinical trial or experiment is at best 50%.
Those results are published in Medical Journals like JAMA; The Journal of the American Medical Association.

It shows a trend, but until the results are duplicated by an independent third party the single trial may be a fluke, a mistake or just a case of bad science. Take the case of Cold Fusion the experiment was done, and it was reproducible, but no one else could reproduce it. Then when scientists came to the lab to see how it was done the same experiment team couldn’t reproduce the experiment either. They put themselves on the line by asking for pier review so I don’t think they were guilty of being dishonest, they had just either made mistakes or it was a fluke.

When a study or experiment produces results they are published in a journal and held up to “pier review.” This means other scientists have to take a look at it and independently verify them. This process takes a while and the first couple of studies may not be enough, then the long term effects have to be checked and even after then their have to be additional studies. This is done until the scientific community is sure of something. Cold medicines have been sold to children for over 100 years, even those below the age of six. Recently, a trend in the higher number of deaths among young children how had taken these medications showed that there might be a problem and the government was called in to hold an official investigation. Rather than be sued the drug companies are going to pull the drug from the market voluntary or allow extra cautionary labeling to be added. But, the central question if something like Children’s Tylenol is effective and safe for children under 6 remains unanswered and no one is going to try and answer it anytime soon. If it is found that a drug like Tylenol is dangerous for those under 6 then people who lost their children can sue the drug companies. If it is proven that they are safe, then just one study isn’t enough and more will have to be made until the unexplained increase in deaths can be explained. That would be expensive and take years to do.

One medical trial shows something CAN be true, and a trend that it MIGHT be true, but until the results are repeated in other studies we can’t be sure. Lately in the news there have been a lot of clinical trials on various good and bad effects of different foods and life styles, and if you wait another month it seems another one comes out that is contradicts the first one. Then there are the long term studies like the Nurses Study which has been going on for longer than a generation. It has shown trends in things like breast cancer and has spawned other studies to verify the result.

But, until that verification is done the study remains in doubt. There was a lot of talk that St. John’s Wart was a natural form of Prosaic. A study showed it to be true and it because it isn’t regulated by the FDA it could be marketed as a natural form of Prosaic. However, before those claims could be written on the bottle another study had to be done. That other study disproved the first and so the story on St. John’s Wart is in doubt, more study is needed. However, it is not in the interest of the producers or St. John’s Wart to have another study done. If the study is done then the results will be taken seriously. If the result is negative then that will decrease the sales of St. John’s War. If the study is positive then that means St. John’s Wart will be proven to be a drug and so it will have to be regulated by the FDA.

Herbal medicine is an accepted form of treatment to many people and it has been for many years. It has been the source of things like Willow Bark tea that when the active ingredient was isolated yielded aspirin. However, for the most part there is no scientific fact behind a lot of herbal medicine. To do the research would create the same problems I mentioned before. So until someone does a study the product can continue to be sold as is in unregulated volumes, but without the ability to make any scientific claims.

For instance it has been proven that women after menopause need extra calcium so a medication like Tums can claim to provide this extra calcium and so put that on the bottle. Also drinks like orange juice can be fortified with extra calcium and so claim health benefits. BUT this is only true for calcium. All the other herbal medicines and supplements are not backed by scientific evidence and there is a good reason not to do the tests so it isn’t done.

The effectiveness of calcium wasn’t proven until it came up in the Nurses Study that post menopausal women had a pattern of calcium deficiency. Then other studies were done until the enough of evidence proved that post menopausal women could gain benefits from extra calcium in their diets. It took several studies, and several years a long and expensive process to reach this point.

The first clinical study wasn’t enough, nor was the second or even the third. Only when a lot of studies showed the increased calcium loss in post menopausal women was the calcium claim considered valid. It takes a long time for a drug to be proven. Drug companies have to spend a lot of time doing this and it gets to be expensive when they have to pay for the drugs that don’t pan our or worse the drugs that prove to be harmful. This is why they have suggested legislation to increase the life of their patents beyond 7 years.

Answer 2

One cannot reliably report the precision of a single trial. Multiple trials can be reported as mean plus or minus a standard deviation.