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L R Shenton

Publications and source records attributed to L R Shenton.

6 recordsLinked to original sources
PubMed1999

Sister chromatid exchange data fit with a mixture of Poisson distributions.

Bowman et al. [K.O. Bowman, Wesley Eddings, Marvin A. Kastenbaum, L. R. Shenton. Sister chromatid exchange data and Gram-Charlier series, Mutat. Res., 403 (1998) 159-169.] have shown that a Gram-Charlier modification of a negative binomial distribution gives a reasonable fit to counts of sister chromatid exchange (SCE) data originally presented by Bender et al. [M.A. Bender, R.J. Preston, R. C. Leonard, B.E. Pyatt, P.C. Gooch, On the distribution of spontaneous SCE in human peripheral blood lymphocytes, Mutat. Res., 281 (1992) 227-232. ]. Here we show that a mixture of a generalized Poisson distributions also fits the data. Advantages of the generalized Poisson mixture include a simplified model involving only four parameters which fits the data more closely according to the chi-squared goodness-of-fit criterion.

Female↗
PubMed1998

Sister chromatid exchange data and Gram-Charlier series.

Bowman et al. [K.O. Bowman, M.A. Kastenbaum, L.R. Shenton, Fitting multi-parameter distributions to SCE data, Mutat. Res., 358 (1996) 15-24.] showed how discrete Pearson and discrete Johnson translation-system distributions may be fitted to sister chromatid exchange (SCE) data presented by Bender et al. [M.A. Bender, R.J. Pearston, R.C. Leonard, B.E. Pyatt, P.C. Gooch, On the distribution of spontaneous SCE in human peripheral blood lymphocytes, Mutat. Res., 281 (1992) 227-232.]. When their performances were measured by the chi-squared test of goodness of fit, these distributions proved to be only moderately better alternatives to the poorly fitting Poisson, binomial, and negative binomial distributions. In this paper, we extend our search for better characterizations of the SCE data by calling upon the Gram-Charlier type B approximation of the negative binomial distribution. We introduce an innovative extension of methods described in a little-known paper by Aitken and Gonin [A.C. Aitken, H.T. Gonin, On fourfold sampling with and without replacement, Proc. R. Soc. Edinburgh, 55 (1934) 114-125.], and show how this leads to fits of the SCE data that, in general, are within acceptable levels of probability. Moreover, we show how a theorem by Cramér [H. Cramér, Mathematical Methods of Statistics, Princeton Univ. Press, 1946.], relating to the scale factor m2/m'1 and its asymptotic distribution, may be used to discriminate between smokers and nonsmokers of the same gender.

Biometry↗
PubMed1996

Fitting multi-parameter distributions to sister chromatid exchange data.

Bender et al. (1992) presented the number of sister chromatid exchanges (SCE) in 50 peripheral blood lymphocytes from each of 393 normal human subjects. In that study of 19650 cells, the number of SCE per cell ranged from 0 to 32. We examine the resulting frequency distributions, and show how they may be fitted, by the method of moments, to discrete Pearson-type and Johnson translation system distributions.

Data Interpretation, Statistical↗