The role of the frailty in the evaluation of injury risk factors for National Basketball Association players

Injuries often occur in sports and, due to medical and economic reasons, it is important to understand the factors that mainly affect the risk of experiencing them. This work aims to explore this field in the context of the National Basketball Association (NBA) league. Thus, the main purpose is to identify the main individual players' characteristics that are associated to a higher risk of suffering an injury in a shorter time, taking into account ten seasons, from the beginning of 2010-2011 season until the end of 2019-2020 season. All the needed information has been retrieved from different big datasets regarding NBA players. The work stands in the survival data analysis framework and, for the purpose, a Cox regression model with frailty has been used. Results suggest that the player's position and the Body Mass Index have a significant effect on the injury's risk. From a methodological point of view, this manuscript provides an insight into the role of the frailty in the model, studying its relationship with the residuals of a mispecified Cox model.