The aim of this study is to develop a measurement tool that measures the level of influence in decision-making of licensed athletes aged 18 years and above who are active in sports. In the stages of creating the candidate form of the scale, writing essays by athletes, scale literature review, and interviews with focus groups were carried out within the scope of "qualitative steps", while hypothesis analyses and validity and reliability analyses were carried out within the scope of "quantitative steps". The expert opinion form prepared with 42 items in the item pool was presented to the experts for their evaluation according to the Lawshe technique. After the expert feedback, 15 items were removed, and 27 items remained. Trial scale form was administered online to 806 active licensed athletes aged 18 and over. Then, the basic assumptions of EFA were tested within the scope of quantitative steps; because of EFA, a 2 dimensional structure consisting of a total of 15 items was obtained. To examine the psychological construct validity of the SECVS, new data were obtained from 493 active licensed athletes by re-collecting data with the 15-item final form formed after EFA and CFA was performed. After CFA, the standardized loadings of the sub-dimensions, the estimated error variances of the variables, the T-values of all items and the goodness of fit values of the model were examined and it was determined that the 2 factor structure of the scale consisting of 15 items was confirmed as a model. In addition, when the convergent and divergent validity and convergent reliability values of the scale were examined after CFA, it was concluded that this scale had …