Berkson’s paradox

Berkson’s paradox happens when given two independent events, if you only consider outcomes where at least one occurs, then they become negatively dependent.  More technically, this paradox occurs when there is ascertainment bias in a study design. Let me provide an example. Consider the case where patients can have diabetes or HIV.  Assume that patients have a positive probability of…

Basket vs. Umbrella clinical trials

How do you determine if a drug is effective?  Typically, biostaticians rely on a randomized control trial where half the patients receive the treatment of interest and the remaining half receive either a placebo or the current standard of care depending on the trial design. Recent advances in cancer, however, call for more sophisticated designs.  Some cancer treatments are only…