Examination of Sample Size in Experimental Designs of Sports Sciences Based on Replication Principle

Replication principle is one fundamental principle of experimental design, and it is also a common means for researchers to control the individual differences of experimental subjects. Following the replication principle can enablefewer experimental errors, higher experimental precision, higher research validity and replicability. Major problems that violate the replicationprinciple of experimental studiesin the field ofsports science are: lack of necessary replications of a certain treatment in a multi-factor experimental design, pseudoreplication caused byrepeated measuresrather than experiments, pseudoreplicationcaused by confusion of experimental analysis units, and no scientific estimation of sample size. These problemshave had a seriousimpacton experiment integrity and resulted in concerns over the reproducibility of experimental results. Researchers should attach importance tothe adherence to the replication principle and to a reasonable sample sizein order to increase the replicability of sports science experiments. In line with the replication principle, emphasis should be put on four issues in experimental studiesof sports sciences:1) Clarify the minimum unit of experimental treatment; 2) Determine the experimental analysis unit to avoid pseudoreplication;3) Determine the minimum amount of replications; 4) Perform sample sizeestimationsscientifically, consider precision and other factorsbesides α value, effect size and statistical power.