The method of double-blind medical studies, when possible and when done correctly, is a very good method. It is excellent for determining the benefits and risks of a treatment when the results are not obvious. As you probably know, the basic idea is to have a control group and a treated group, such that while the study is in progress neither patients or persons directly administering the study know which patients belong to which group. The control group is administered a placebo which is indistinguishable in form from the real medicine, and the treated group is of course administered the real medicine. Then the results are compared at the end of the study to see if the treatment offers any benefit at acceptable risk.
There are ample examples where the integrity of studies has been compromised by dishonest researchers, and this could of course happen with any method of study. But a more subtle way of controlling the result of double-blind is by selection of the placebo. Ideally, a placebo should have no effect on the patients. However, sometimes the kind of placebo used is not even mentioned in the published study. So, for example if the real medicine causes patients to feel bad, a placebo could be chosen to also make the patients feel bad. Then they could publish that the medicine had no worse side effects than the placebo, making the medicine appear better than it really is.
A common way of rigging studies about vitamins is to use synthetic vitamins, many of which are demonstrably inferior to natural vitamins. Obviously any such study is going to give less favorable results for vitamins.
But probably the biggest ruse with respect to double-blind is that conventional medicine discounts the benefits of any alternative treatment that has not been subjected to double-blind study. I would say they are correct in cases where the benefits of a treatment are not obvious. But if the results are clear and obvious and many, and are results which are not achieved with conventional medicine, then the insistence on double-blind studies is just a ruse to deny that anything but conventional medicine can offer any benefit.
But, conventional medicine does not insist on double-blind as the only standard for evaluating their own therapies. For example, heart bypass surgery could hardly be studied by the double-blind method, but yet they emphatically affirm that it has benefits. And on what basis do they affirm this? On the basis that there is percieved and measurable relief after the surgery. And they are correct, at least over the short term. But this is the same logic which they refuse to accept when evaluting alternative therapies, such as chelation therapy, which in my personal experience gives better results than bypass surgery, at much less inconvenience and expense.
Another example is conventional surgery, chemotherapy and radiation for cancer. Since every case of cancer is highly unique, it seems to me clearly impossible to compare one case with another, much less possible to compare groups of cancer patients. Furthermore, I expect that most people would consider double-blind studies of cancer unethical because you would in effect be letting the control group die. Therefore it seems to me that accurate results from double-blind studies of cancer are impossible. (If this is not correct, please someone let me know.) It seems that most cases of conventional cancer treatments that I am aware of have failed, with only a few giving good results. But in spite of it not being proven by double-blind studies, they strongly believe in it, or else they would not do it routinely.
It can be shown mathematically that when results are obvious and numerous from a given treatment, there exists a high degree of certainty that the treatment is the reason for the results. Suppose that the odds of condition X improving by random chance (that is without any treatment) are 1 in 1000, and suppose there are 10 cases of obvious benefit after receiving treatment Y. The odds of all 10 cases occurring by random chance is 1 in 1000 raised to the 10th power, or
1 in 1,000,000,000,000,000,000,000,000,000,000.
Now in my estimation, that is virtual certainty that the benefit was a result of treatment Y. But if you have 100 or 1000 such results, just do the math and then you are talking about astronomically large numbers. Are there any double-blind studies that can demonstrate that kind of mathematical certainty? I seriously doubt it.
So the ruse of double-blind is that it is used to discount results of high mathematical certainty if the results did not come from a double-blind study, and the results are not to the liking of the medical establishment. As I explained above, they apply one standard to their own treatments and a different one to alternative treatments.