WTN: Your Confidence Level Explained

The World Tennis Number (WTN) is a global rating system developed by the International Tennis Federation (ITF) to provide a standardised measure of a player's skill level, ranging from 40 (closer to beginner) to 1 (elite professional). A key component of this system is the Confidence Level, ranging from 0 to 100%, which indicates how confident we are in a player's WTN based on the amount and recency of match data available.

Understanding the Confidence Level

The Confidence Level reflects how certain the WTN algorithm is about a player's rating. It's visually represented by a checkmark next to the player's WTN:

• High Confidence (Dark Blue Checkmark): Indicates a high degree of confidence (≥70%) in the accuracy of the player's WTN. When a player has high confidence (≥70%), we consider their number verified.
• Low Confidence (Grey Checkmark): Signifies a lower confidence level (≤70%), often due to limited or outdated match data.

These colour-coded checkmarks help players and organisers quickly assess the reliability of a given WTN. Note that some nations use the Confidence Feature slightly differently, i.e.. the USTA offer a three-tiered approach to how it is displayed.

Factors Influencing Confidence Level

Several factors affect a player's Confidence Level:

• Match Frequency: Regular play enhances the algorithm's confidence. For instance, completing 15 sets over five consecutive weeks can elevate a player's Confidence Level to high.
• Recency of Matches: Recent match data is more influential. Inactivity can lead to a decline in Confidence Level, as the algorithm accounts for increased uncertainty.
• Diversity of Opponents: Competing against a variety of players provides a broader data set, improving the accuracy and confidence of the WTN.

Impact of Confidence Level on WTN

The Confidence Level directly influences the stability and responsiveness of a player's WTN:

• High Confidence: With ample data, the WTN becomes more stable, and individual match results cause smaller adjustments.
• Low Confidence: Limited data leads to greater fluctuations in the WTN after each match, as the algorithm recalibrates based on new information.

For example, two players with identical WTNs but differing Confidence Levels will experience different rating changes from the same match outcome; the player with lower confidence will see more significant shifts.

Enhancing Your Confidence Level

To improve your Confidence Level:

• Play Regular Matches: Consistent participation ensures the algorithm has up to date information, bolstering confidence in your WTN.
• Engage with Diverse Opponents: Facing a range of players enriches the data quality, leading to a more accurate and reliable WTN.

By understanding and actively managing your Confidence Level, you can ensure your WTN accurately reflects your current skill level, facilitating better matchups and personal development within the global tennis community.