RT Book, Section A1 White, Susan E. SR Print(0) ID 1176051349 T1 Study Designs in Medical Research T2 Basic & Clinical Biostatistics, 5e YR 2020 FD 2020 PB McGraw-Hill Education PP New York, NY SN 9781260455366 LK accessmedicine.mhmedical.com/content.aspx?aid=1176051349 RD 2024/10/08 AB KEY CONCEPTSStudy designs in medicine fall into two categories: studies in which subjects are observed, and studies in which the effect of an intervention is observed.Observational studies may be forward-looking (cohort), backward-looking (case–control), or looking at simultaneous events (cross-sectional). Cohort studies generally provide stronger evidence than the other two designs.Studies that examine patient outcomes are increasingly published in the literature; they focus on specific topics, such as resource utilization, functional status, quality of life, patient satisfaction, and cost-effectiveness.Studies with interventions are called experiments or clinical trials. They provide stronger evidence than observational studies.The single best way to minimize bias is to randomly select subjects in observational studies or randomly assign subjects to different treatment arms in clinical trials.Bias occurs when the way a study is designed or carried out causes an error in the results and conclusions. Bias can be due to the manner in which subjects are selected or data are collected and analyzed.Clinical trials without controls (subjects who do not receive the intervention) are difficult to interpret and do not provide strong evidence.Each study design has specific advantages and disadvantages.