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Proceedings Paper

Divergence as a measure of visual recognition: bias and errors caused by small samples
Author(s): Manhot Lau; Takashi Okagaki
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Paper Abstract

Total divergence has been shown to be a useful measure of performance of visual recognition processes. Measurement and comparison of divergences using samples require statistical processing and sample size becomes an important factor in practical applications when sample sizes are small. We recently completed a numerical study on the applicability of total divergence to a medical Pap test process in small samples. This study suggested that in order to keep measurement biases within +/- 0.5 decits, 100 - 200 samples of cytology- histology pairs were required in the best classifications of 3, 4, and 5 category-states. At these sample sizes, measurement errors (standard errors) were also contained within +/- 0.5 decits. This study also confirmed that previously reported, over-estimated propagated errors in small samples were in fact over-estimation, and that their use for testing a null hypothesis was valid. The number of samples with indefinable statistics due to a zero denominator can be as high as 30% when the sample sizes were 500 for 3, 4, and 5 category-state classifications. Biases due to small samples were positive for most category-states except for the optimum 3 category-states, in which bias changed to negative (bias inversion), and observed errors of total divergence paradoxically decreased as N decreased (error-sample paradox) for a small sample size (N < 700).

Paper Details

Date Published: 1 November 1991
PDF: 9 pages
Proc. SPIE 1606, Visual Communications and Image Processing '91: Image Processing, (1 November 1991); doi: 10.1117/12.50368
Show Author Affiliations
Manhot Lau, Univ. of Minnesota Medical School (United States)
Takashi Okagaki, Univ. of Minnesota Medical School (United States)

Published in SPIE Proceedings Vol. 1606:
Visual Communications and Image Processing '91: Image Processing
Kou-Hu Tzou; Toshio Koga, Editor(s)

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