There are several studies in the literature that indicate a number of tests to measure hamstring flexibility. Perform a brief literature search on Google Scholar(use "validity hamstring flexibility") and use the information in the abstracts to determine which test is the most accurate. In other words, which test has the highest concurrent validity with the criterion test (also, what is the criterion for hamstring flexibility?). For example, the criterion test for body composition is underwater weighing, to which the validity of other measurements such as skinfolds are based. Be sure to support your posting with validity measurements reported in the literature and cite references when appropriate.