While motion analysis and biomechanics constitute important areas in performance analysis, one of the most popular and fundamental pieces of performance analysis in sport is the use of notational analysis. Notational analysis is the identification and analysis of critical patterns and events in a performance that lead to a successful outcome. Hughes (2004) defined notational analysis as "a procedure that could be used in any discipline that requires assessment and analysis of performance". The information used for notational analysis is usually gathered by observing a team's performance in a competitive environment. By notating numerous events that take place on the pitch, such as striker positioning, defenders' tackle success rate or midfielders pass completion rate, an analyst can identify strengths and weaknesses and provide these results to coaches who then use them to adapt training sessions or share accurate feedback with players and the entire team.
The importance of notational analysis comes from the limited recalling ability that coaches, as human beings, have when remembering specifics of the performance of their teams, and how these can be biased by their beliefs and other motives. As Hughes and Franks described, by receiving objective data of what happened during a game, a coach can make a more informed decision by enhancing his or her abilities to accurately assess the events of a game and improving the quality of feedback he is able to provide to the players. A big miss by a striker might be recalled by coaches and other players more vividly than the same's striker effective positioning or successful dribbling in the same game. At a professional level, we often hear pundits and fans rate a player's performance in a game based on a small number of noticeable actions that took place, such as a missed penalty or a defender's mistake that led to a one-on-one chance by the opposition team. However, through notational analysis, a more complete view of that player's performance may provide a more accurate perspective on the players contribution in the game and inform any future decisions towards that player, such as training structure or upcoming match presence.
Different teams in different sports will define their own frameworks of performance indicators that allows them to identify the areas in the game they are most interested in evaluating. This means that there is a wide range of information that is captured today in notational analysis depending on the environment the analyst is working in. This is in part due to the lack of a common set of performance indicators being identified as the key to sporting success, particularly in team sports where it is practically impossible to account for every single events that could lead to winning a match. A football team may consider percentage of shots on target, possession percentage and pass completion rate to be their performance indicators to benchmark themselves against for a game, while a different team in the same sport may want to consider possession percentage on the opposition's last third, defensive tackles won and total number of shots. As Hughes stated in 2011, while all these may be considered valid information to collect, the lack of a common framework across sport may be slowing down the research and analysis to develop notational analysis further.
There are certain challenges in notational analysis, particularly when it comes to live events. A single analyst notating events and patterns in real time may be subjected to human error or miss certain actions. This is why most sport statistics companies and elite sporting organisations employ several analysts to collect the same performance indicators on a live game, allowing to compare notated statistics between analysts with the purpose of improving the accuracy of the data collected. Another challenge of the notational analysis process is subjectivity, were events notated that have a certain degree of ambiguity may be captured differently by different analysts. While notational analysis aims to add objectivity when evaluating a team's performance by quantifying the events, it is possible that the definition of such events may change depending on the interpretation the analyst capturing the event has on that action.
During the last two decades, a large number of new technologies have developed the methods and effectiveness of notational analysis in sport. While traditional analyst often used a pen and a notepad to notate all the various events they considered relevant, technologies like Opta, Dartfish or Sportscode have become a central asset for notational analysts in the industry. The use of a video camera and a video analysis software can now provide analyst with a wide range of features and tools to collect as much information as they require to assess performance against specific performance indicators.