... selection bias) is the type of confounding bias of which clinicians may be aware, though it is important to point out that confounding bias is not just limited to clinicians selecting patients non-randomly ... investi- gator might be biased in favor of what is being studied. In more objective outcomes (such as mortality), this bias will be less likely. Blinding (single – of the subject, double – of the ... developed, the relevance of sample size for confound- ing bias was identied by a nineteenth-century founder of statistics, Quetelet, who wrote in 1835: “e greater the number of individuals observed,...