A validation study generates enough evidence to prove that tests being used are precise measurements of performance. It is extremely important for researchers to "validate" their studies in order to prove that they are reproducible. This lends credibility to their findings. In spinal cord injury (SCI) research, as in any medical research, it is essential that tests be accurate and reproducible by other researchers at other centers. Otherwise, there would be no way to compare results and to know whether treatments are truly making a difference. Validation studies such as the Walking Index for Spinal Cord Injury (WISCI) scale lay the groundwork for additional research studies because, armed with a reliable measurement tool, investigators can quantify results that they were previously unable to document.