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NETA - a program for calculating the Neyman Type A confidence limits |
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Introduction to NETA
The Neyman type A distribution, a generalized, "contagious", Poisson distribution finds application in a number of disciplines such as biology, physics and economy. It was first described by Jerzy Neyman in 1939 (Neyman 1939). In radiation biology it best describes the distribution of chromosomal aberrations in cells that were exposed to neutrons, alpha radiation or heavy ions.
We have developed a freeware program for calculating the 95% confidence limits of Neyman type A-distributed events. The program can be downloaded here. The algorithm is based on the frequentist method published by Jerzy Neyman (1939). Although it has been developed in response to the requirements of radiation biology, it can find application in other fields of research.
Description of NETA
The program NETA is easy to use:
it has only one window where the user enters the observed distribution.
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A screenshot of NETA
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Following entry of the distribution the user presses the COUNT button. NETA verifies if the distribution is Poissonian by the u-test as described by Edwards et al. (1979). In the case of a Poissonian distribution the 95% confidence limits (LCL - lower confidence limit and UCL - upper confidence limit) are calculated for a Poisson distribution as described by Deperas et al. (2007). When the distribution is not Poissonian NETA verifies if it is a Neyman type A distribution by performing a chi-square goodness-of-fit test. The confidence limits are calculated when the distribution is a Neyman type A. Otherwise an error message is displayed. In addition to the confidence limits NETA also gives some information about the statistics of the entered distribution. The entered data can be saved and files can be opened. The CLEAR DATA button is used to delete the data: NETA is now ready to perform a new calculation.
About the authors
Josselin Morand Institute for Energy - JRC Petten, European Commission
Joanna Deperas-Standylo Institute of Nuclear Chemistry and Technology, Warsaw,
Poland
and Joint Nuclear
Research Centre, Dubna, Russia
Witold Urbanik Economic University, Wroclaw, Poland
Andrzej Wojcik Institute of Nuclear Chemistry and Technology, Warsaw, and Department of
Radiobiology and Immunology, Swiętokrzyska Academy, Kielce, Poland
Please forward questions or comments to any of the authors.
References
Deperas J., Szłuińska M., Deperas-Kaminska M., Edwards, A., Lloyd D., Lindholm C., Romm H., Roy L., Moss R., Morand J., and Wojcik A. (2007) CABAS - a freely available PC program for fitting calibration curves in chromosome aberration dosimetry. Radiation Protection Dosimetry, in press.
Edwards A. A., Lloyd D. C., and Purrot R. J. (1979). Radiation induced chromosome aberrations and the Poisson distribution. Radiation and Environmental Biophysics 16: 89-100.
Neyman J. (1939). On a new class of "contagious" distribution, applicable in entomology and bacteriology. Am. Math. Stat. 10: 35-55.
last updated on 20.07.2007 by Andrzej Wojcik