Maintaining variance and k-medians over data stream windows Brian Babcock, Mayur Datar, Rajeev Motwani, and Liadan O'Callaghan   View Paper (PDF)   Return to Streams and Indexing Abstract 1/2 is a parameter which trades off the space bound with the approximation factor of O(2^O(1/tau)). BIBTEX @inproceedings       {DBLP:conf/pods/BabcockDMO03,   author    = {Brian Babcock and                 Mayur Datar and                 Rajeev Motwani and                 Liadan O'Callaghan},    booktitle = {PODS},    title     = {Maintaining variance and k-medians over data stream windows.},    pages     = {234-243},    year      = {2003},    url       = {db/conf/pods/pods2003.html#BabcockDMO03},    ee        = {http://doi.acm.org/10.1145/773153.773176},    crossref  = {conf/pods/2003},    bibsource = {DBLP, http://dblp.uni-trier.de}  } ©2004 Association for Computing Machinery