- deficiencies in the reporting methodology https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3554513/
- a bit of incorrect retraction https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3899113/
- a fun one on systematic reviews https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4785311/
- regarding missing data https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4748550/
- a paywalled abstract about power https://www.ncbi.nlm.nih.gov/pubmed/26677241
- on sample size calculations https://www.ncbi.nlm.nih.gov/pubmed/25523375
- aaand a fun one on selection bias https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566301/
All found within 10 minutes...
We could go on like that for hours with this sizing contest. I do not expect to convince you. You will, if you put the time and effort into it, find other studies saying the opposite (although being less sexy for publishers, they will be harder to find). If you are somewhat knowledgeable in the field of statistics, please take a look a the numbers, as I am quite sure you will find them appalling (19% of study population missing outcome data and 27.9% underpowered studies, anyone?)
http://www.jclinepi.com/article/S0895-4356(16)00147-5/abstra...
What the OP is referring to isn't unique to MDs, it's endemic to much biomedical research today. I blame it on lack of tenure protections and science-as-university-income, which in many cases ultimately stems from indirect costs charged to federal grants, or the current grant system.
For me, the concerns mentioned in this thread about scientific research and MD training in particular, bring up bigger issues pertaining to the culture of hierarchy in medicine and its implications for quality of care and competition in service provision and training models.
What do you consider a well-known, credible medical professional? A Harvard professor? I happen to have worked with world-renowed clinical researchers, and I have nothing but disrespect for their scientific abilities. I do however, value their clinical teachings very much, and I am thankful for the training they provided in the clinics.
I am frankly not motivated enough to look for papers about it, and I clearly speak from my own experience. I do know that the proportion of research considered as valid is very difficult to estimate, though. If you are interested in "evidence-based medicine", I am sure you know PubMed and related websites. At this point however, I find it extremely difficult to believe any medical paper containing statistics.