What causes infertility issues?
What are some current treatments for infertility?A study was conducted to assess whether ankle joint laxity was a risk factor for first time ankle sprain. Twenty soccer players without a history of ankle sprain were evaluated prior to the beginning of the playing season. A clinician performed passive ankle movement tests. Using the information from the movement tests the clinician then rated ankle joint laxity using the following scale: absent, minimal, moderate, maximal. At the end of the soccer season players were categorized as experiencing at least one ankle sprain during the season or experiencing no ankle sprain. What is the independent variable in the study?
a. Time interval between pre- and post-season
b. Amount of ankle joint laxity
c. The number of soccer games played in the season
d. The group of soccer players