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Activity Number:
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90
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Type:
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Contributed
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Date/Time:
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Monday, August 9, 2004 : 9:00 AM to 10:50 AM
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Sponsor:
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Biometrics Section
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| Abstract - #301481 |
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Title:
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Smoothing of Multimodal Histograms to Attain Unimodality: Application to Telomere Lengths and Clonal Heterogeneity in Leukemia Patients
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Author(s):
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Martin L. Lesser*+ and Julia Y. Tai and Rajendra Damle and Nicholas Chiorazzi
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Companies:
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North Shore LIJ Research Institute and North Shore LIJ Research Institute and North Shore LIJ Research Institute and North Shore LIJ Research Institute
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Address:
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1129 Northern Blvd. Suite 302, Manhasset, NY, 11030,
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Keywords:
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multimodality ; histograms ; smoothing ; clonal heterogeneity
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Abstract:
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Do observers agree on when a multimodal histogram (hgm) becomes unimodal after repeated smoothing? Does the point at which unimodality occurred result in clusters of hgms? Telomeres (tels) are the distal ends of chromosomes that become shorter as cells age. By studying tel lengths in leukemia patients (pts), patterns of clonal heterogeneity may be identified. Hgms of tel lengths were created for each of 70 leukemia pts. Median no. tels in the hgms was 1,693. Hgms showed one or two large modes and multiple local maxima in the tails. Each hgm was then repeatedly smoothed with a kernel density estimator with increasing bandwidths (BW). Four observers recorded the minimum BW at which the hgm appeared unimodal. The intraclass correlation for the four observers was 0.8, indicating generally good agreement on a highly subjective criterion. After mean BW across observers was computed for each hgm, the distribution of the 70 mean BWs suggested clusters of three or four groups. Multiple observers can agree as to when a smoothed histogram becomes unimodal. Some leukemia pts may have multimodal hgms, suggesting clonal heterogeneity.
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