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PubMed1994

Precision of incidence predictions based on Poisson distributed observations.

Disease incidence predictions are useful for a number of administrative and scientific purposes. The simplest ones are made using trend extrapolation, on either an arithmetic or a logarithmic scale. This paper shows how approximate confidence prediction intervals can be calculated for such predictions, both for the total number of cases and for the age-adjusted incidence rates, by assuming Poisson distribution of the age and period specific numbers of incident cases. Generalizations for prediction models, for example, using power families and extra-Poisson variation, are also presented. Cancer incidence predictions for the Stockholm-Gotland Oncological Region in Sweden are used as an example.

Adult↗
PubMed1987

Confirmation of an abnormal (non-Poisson) distribution of sperm from some infertile men in the hamster-ovum test.

The present study was carried out to investigate an earlier report that stated that some men of infertile couples (patients), but not normal donors, have an abnormal (non-Poison) distribution of penetrating sperm among ova in the hamster-ovum test. Semen samples from 60 men, 24 proven fathers and 36 patients, were analyzed for agreement with the theoretical Poisson distribution (PD). Most of the fathers (23 of 24) fit PD well, but 10 of the patients did not. The overall (group) fit of fathers is good, but that of the patients is poor. Patients, but not fathers, are heterogeneous in their agreement with PD; about 25% fit poorly whereas more than 50% fit well. The 25% fitting poorly may often be those patients who are truly infertile (even when their wives are actually fertile).

Adult↗
PubMed1975

Non-Poisson distribution in time of small- and large-mode miniature end-plate potentials.

Minature end-plate potentials (MEPP's) were recorded from frog (Rana pipiens) sartorius muscle cells of 60--80 mum diam; MEPP frequency remained constant up to 3 h and was 100 times greater in 80-mum cells than in 6-mum cells. Rapid cooling or heating of preparations initiated or accentuated bursts of MEPP's. Records from cells under control conditions and from cells where the MEPP population had been reduced to the small mode showed many instances of small clusters of MEPP's occurring within 100-ms intervals, indicating quantal release interdependencies. Some small cells initially generated many large MEPP's 2 or more times the average amplitude and fewer small clusters. Analysis of the occurrence of both large- and small-mode MEPP's for both 1.0-s and 100-ms nonoverlapping bins demonstrated a highly significant deviation from a Poisson distribution with significance increasing with decreasing cell diameter and/or MEPP frequency. It is suggested that doublet MEPP's are generated from one release site and that large bursts results from the activity of several release sites, since the size of bursts decreases with cell diameter (junctional area). It is concluded that release characteristics are the same for large-mode (classical) and small-mode MEPP's and that the occurrence of MEPP's is not Poisson.

Animals↗
PubMed1979

Radiation induced chromosome aberrations and the Poisson distribution.

Data on the distribution of dicentrics and acentrics observed when human lymphocytes are cultured for 48 h after irradiation by X-rays, gamma-rays, and neutrons are presented. Analysis shows that for dicentrics, the observed distribution for X-rays, gamma-rays, and fission neutrons may be described by Poisson statistics but for higher energy neutrons overdispersion is observed. The phenomenon of overdispersion is also observed for acentrics irrespective of the radiation used. The possibility that overdispersion results from the variations of dose in sensitive sites leads to the conclusion that for dicentrics the site size is considerably larger than the 1--2 micrometer diameter derived by applying the dual action theory to the dose effect relationships. This larger site may well be the cell nucleus.

Cells, Cultured↗
PubMed1986

Application of Poisson distribution theory to the zona-free hamster oocyte penetration test to assess sperm function of men with asthenozoospermia.

Assessments of the penetrating potential of human spermatozoa were carried out using the zona-free hamster oocyte penetration test on 4 groups of subjects exhibiting normal fertility, idiopathic asthenozoospermia(less than 40% motility), asthenozoospermia associated with varicocele and oligoaesthenozoospermia (less than 20 X 10(6) spermatozoa/ml and less than 40% motility). When the Poisson model was used to correct the results of the in-vitro penetration experiments for differences in motile sperm concentration, significant differences were apparent between the normal fertile controls and all 3 categories of asthenozoospermic patient. Furthermore, the penetrating ability of the motile spermatozoa from patients presenting with a varicocele or oligoaesthenozoospermia was significantly less than that for the group in which asthenozoospermia was the only detectable defect. These results emphasize the practical significance of the Poisson model in the analysis of male fertility and demonstrate that the asthenozoospermic condition is associated with a significant reduction in the fertilizing potential of the motile spermatozoa.

Animals↗