[Lisa_seminaires] [Lisa_montreal] [Tea Talk] extra talk this afternoon 15:30, AA4488, on Ranking

Yoshua Bengio yoshua.umontreal at gmail.com
Ven 11 Mai 09:40:03 EDT 2018


We have an extra tea-talk this afternoon at 15:30 in room AA4488:
https://www.gerad.ca/fr/events/1589

A WEIGHTED CORRELATION INDEX FOR RANKINGS WITH TIESSebastiano Vigna
<http://vigna.di.unimi.it/> – Università degli Studi di Milano, Italie

Understanding the correlation between two different scores for the same set
of items is a common problem in information retrieval, and the most
commonly used statistics that quantifies this correlation is Kendall's tau.
However, the standard definition fails to capture that discordances between
items with high rank are more important than those between items with low
rank. Recently, a new measure of correlation based on average precision has
been proposed to solve this problem, but like many alternative proposals in
the literature it assumes that there are no ties in the scores. This is a
major deficiency in a number of contexts, and in particular while comparing
centrality scores on large graphs, as the obvious baseline, in-degree, has
a very large number of ties in web and social graphs. We propose to extend
Kendall's definition in a natural way to take into account weights in the
presence of ties. We prove a number of interesting mathematical properties
of our generalization and describe an O(nlogn) algorithm for its
computation. We also validate the usefulness of our weighted measure of
correlation using experimental data.


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