Limitations include lack of control or comparison group, lack of randomization of participants, and small sample size. (cebc4cw.org)
The latter are examples of Mendelian randomization studies, enabled by the cheap genotyping of the past decade, which can be considered Nature's own randomized clinical trials, and like RCTs, offer some of the best evidence or refutations of a causal role for risk markers. (nutritionfacts.org)
• The most recent dose of olaratumab must have been received within 180 days of randomization in this study. (vicc.org)