PSI Tennis App 1.3.3

The Performance Stat Index (PSI), introduced in 2009, serves as a comprehensive analytical tool for players on the ATP Challenger circuit. It was designed to help athletes identify their strengths and weaknesses while providing an overarching assessment of their performance. Subsequently, two additional indexes were incorporated to cater to players in intermediate and advanced ranks, just below the elite level associated with the ATP Challenger circuit.

• Index 1: players with UTRs 3-6.99
• Index 2: players with UTRs 7-10.99
• Index 3: players with UTRs 11+

The PSI employs a statistical algorithm that calculates the total ratio difference between won (Good Shots) and lost (Bad Shots) points in a set. This algorithm subsequently derives the average points won or lost per game within that set, referred to as PSI Ratings.

Good Shots are defined as unreturned serves, winners, and forced errors, while Bad Shots include double faults, unforced errors, and missed makeable shots. After the completion of a set, both competitors receive their respective PSI Ratings; a positive rating indicates a greater number of points won than lost, whereas a negative rating signifies the opposite.

The PSI framework hinges on three core indexes that formulate the PSI Grades across various performance areas: SERVICE PERFORMANCE, GROUNDSTROKE AND AUXILIARY, and OVERALL PERFORMANCE. Each area is assessed through standardized parameters of Good Shot/Bad Shot point averages, informed by extensive research derived from charting competitive matches at multiple levels of play.

The established PSI Performance Grades include:

• Excellent Performance
• Above Average Performance
• Solid Performance
• Below Average Performance
• Poor Performance

The variability in the total number of shots recorded may lead to fluctuating ratios, ranging from a 1:1 to a 1:1.9 ratio or beyond. For reference, below are threshold examples corresponding to Index 2 overall performance parameters:

• Excellent Performance: 3 Good Shots to 1 Bad Shot Ratio
• Above Average Performance: 2 Good Shots to 1 Bad Shot Ratio
• Solid Performance: 1 Good Shot to 1 Bad Shot Ratio
• Below Average Performance: 1 Good Shot to 2 Bad Shots Ratio
• Poor Performance: 1 Good Shot to 3 Bad Shots Ratio

The thresholds for achieving a Solid grade differ between Indexes; Index 1 features a lower threshold while Index 3 has a higher one.

Terms of Use EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/