I always appreciate posters who make a clear distinction between opinion, personal experience, and factual information. As a researcher in other fields, I have learned the value of assessing the quality of evidence. From highest to lowest, evidence can be categorized by quality: 1) meta-analyses (a report on a group of randomized controlled trial studies that both summarizes overall findings and which critiques the quality of the studies analyzed in the meta-analysis), 2) individual randomized controlled trial studies published in peer reviewed journals, 3) non-randomized but otherwise well-designed studies published in peer reviewed journals, 4) well designed non-experimental studies published in peer reviewed journals, 5) opinions from recognized expert institutions and individuals that are based on clinical evidence, descriptive studies, or committee reports, and 6) the opinions of colleagues and peers. Most of what is posted in the discussion forums of Martial Talk falls into category 6, the lowest quality of evidence. That doesn't mean that sharing opinions with each other is a worthless endeavor. On the contrary, I learn a lot from reading what people have to say here, but what I learn is often more about the varied ways that people experience being a martial artist than about the art itself. Of course, not all issues in Taekwondo or other martial arts have been researched highly or even at all. Hence, some issues simply do not have high quality evidence available from which we can learn. But, when it is possible here on Martial Talk, I particularly value information that is presented with references that allow me to conduct my own research into the issue. And, I particularly value information that is as close to the source as possible given the state of evidence in this field.
What would be examples of numbers 1 through 4? I'm trying to read those but they don't make much sense to me.