ABSTRACT
Once the hypothesis has been formulated, including what outcome variables will be used to evaluate the effect of the intervention, the next major challenge that must be addressed is the specification of the experimental design. Getting the correct design for the question being posed is critical since no amount of statistical analysis can adjust for an inadequate or inappropriate design. While the typical clinical trial design is usually simpler than many of the classical experimental designs available (Cochran and Cox 1957; Cox 1958; Fisher 1925; Fisher 1935), there are still many choices that are being used (Friedman et al. 1998).
