PurposeTo explain the concept and procedure of random allocation as used in a randomized controlled study.MethodsWe explain the general concept of random allocation and demonstrate how to perform the procedure easily and how to report it in a paper.

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

WhyCalculating the sample size is essential to reduce the cost of a study and to prove the hypothesis effectively.HowReferring to pilot studies and previous research studies, we can choose a proper hypothesis and simplify the studies by using a website or Microsoft Excel sheet that contains formulas for calculating sample size in the beginning stage of the study.MoreThere are numerous formulas for calculating the sample size for complicated statistics and studies, but most studies can use basic calculating methods for sample size calculation.

The results for lengths and length change patterns of various MPFL fibers are expected to serve as a theoretical background for anatomic double-bundle MPFL reconstruction.

In lumbar posterior interbody fusion surgery, CaO-SiO-PO-BO glass ceramics spacer showed a similar fusion rates and clinical outcomes compared with titanium cage.