Problem: How is evidence recommended for clinical practice using the appraisal system adopted by the NHMRC? a- The study design eliminates all internal and external validity threats, so the evidence consists only of systematic effects with no random effects. b- The NHMRC recommends treatments based on that evidence. c- Most patients would choose the recommended treatment, given that benefits of the treatment exceed its risks, burdens and costs. d- Treatment based on that evidence are efficacious, effective and efficient.