Average Precision at Cutoff k under Random Rankings: Expectation and Variance

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Hauptverfasser: Manzhos, Tetiana, Ianevych, Tetiana, Melnyk, Olga
Format: Preprint
Veröffentlicht: 2025
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author Manzhos, Tetiana
Ianevych, Tetiana
Melnyk, Olga
author_facet Manzhos, Tetiana
Ianevych, Tetiana
Melnyk, Olga
contents Recommender systems and information retrieval platforms rely on ranking algorithms to present the most relevant items to users, thereby improving engagement and satisfaction. Assessing the quality of these rankings requires reliable evaluation metrics. Among them, Mean Average Precision at cutoff k (MAP@k) is widely used, as it accounts for both the relevance of items and their positions in the list. In this paper, the expectation and variance of Average Precision at k (AP@k) are derived since they can be used as biselines for MAP@k. Here, we covered two widely used evaluation models: offline and online. The expectation establishes the baseline, indicating the level of MAP@k that can be achieved by pure chance. The variance complements this baseline by quantifying the extent of random fluctuations, enabling a more reliable interpretation of observed scores.
format Preprint
id arxiv_https___arxiv_org_abs_2511_02571
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Average Precision at Cutoff k under Random Rankings: Expectation and Variance
Manzhos, Tetiana
Ianevych, Tetiana
Melnyk, Olga
Information Retrieval
Probability
Primary 60E05, 60C05, Secondary 62R07, 68T05
Recommender systems and information retrieval platforms rely on ranking algorithms to present the most relevant items to users, thereby improving engagement and satisfaction. Assessing the quality of these rankings requires reliable evaluation metrics. Among them, Mean Average Precision at cutoff k (MAP@k) is widely used, as it accounts for both the relevance of items and their positions in the list. In this paper, the expectation and variance of Average Precision at k (AP@k) are derived since they can be used as biselines for MAP@k. Here, we covered two widely used evaluation models: offline and online. The expectation establishes the baseline, indicating the level of MAP@k that can be achieved by pure chance. The variance complements this baseline by quantifying the extent of random fluctuations, enabling a more reliable interpretation of observed scores.
title Average Precision at Cutoff k under Random Rankings: Expectation and Variance
topic Information Retrieval
Probability
Primary 60E05, 60C05, Secondary 62R07, 68T05
url https://arxiv.org/abs/2511.02571