Author(s): BOZDECH, M., CZYZ, S.H., Institution: MASARYK UNIVERSITY, Country: CZECH REPUBLIC, Abstract-ID: 1460

INTRODUCTION:
In junior tennis, ranking-based success (Total Ranking Points; TRP) and efficiency-based performance (points per tournament; PPE) are related but non-identical constructs. Elite status is often defined by arbitrary percentiles, limiting interpretability and policy relevance. To derive structurally grounded PPE cut-offs for female junior players and to examine whether fixed benchmarks remain temporally robust and prospectively adequate as longitudinal reference standards.
METHODS:
Longitudinal year-end data from 8,520 female junior (5,925 unique players) players competing in the ITF World Tennis Tour Juniors between 2004 and 2025 were analysed using publicly available ITF records. Performance was quantified using TRP and PPE, calculated as TRP divided by the number of ITF-sanctioned tournament entries within each calendar year. Elite status was defined annually using data-driven knee estimation of TRP percentile–value curves, capturing the structural transition between the elite segment and the remainder of the distribution. Given the narrow elite segment among girls, discipline-specific PPE cut-offs (Singles, Doubles, Total) were estimated using pooled logistic regression across years, while preserving year-specific TRP-defined elite classifications. Discrimination was evaluated using ROC analysis and the Youden index. As contextual support, chronological age (calendar year minus year of birth; ages 12–18 years) was compared above versus below fixed PPE cut-offs using the Mann–Whitney U test, with rank-biserial correlation. Temporal robustness was assessed by applying fixed PPE cut-offs to year-specific elite definitions and computing annual sensitivity and false negative rate (FNR). Prospective adequacy for 2026–2030 was evaluated by forecasting logit-transformed sensitivity using a Bayesian-inspired additive time-series model.
RESULTS:
Fixed PPE cut-offs with strong to excellent discrimination were identified: Singles = 9.17 (AUC = 0.91), Doubles = 15.29 (AUC = 0.89), and Total = 6.76 (AUC = 0.90). Players above cut-offs were modestly older across domains (median 17 vs 16 years), with statistically significant differences after correction (RBC = 0.16–0.28), supporting developmental interpretability without conflating efficiency with age. Misclassification drift analyses demonstrated persistently high elite capture under fixed cut-offs, with only transient deviations around 2020. Forecasts indicated near-complete elite capture through 2030 for Singles and Total, with wider uncertainty for Doubles reflecting greater structural volatility.
CONCLUSION:
Performance efficiency thresholds anchored to ranking structure can be derived as interpretable fixed benchmarks that remain temporally robust in female junior tennis. The proposed framework links ranking structure to policy-relevant efficiency standards and provides a transparent basis for longitudinal monitoring and forward-looking evaluation.