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Re-examination of the statistical methods used to determine the number of point counts needed for micropaleontological quantitative research

Published online by Cambridge University Press:  19 May 2016

R. Timothy Patterson  and
Evan Fishbein
R. Timothy Patterson
Affiliation:
Department of Earth Sciences, Carleton University, Ottawa, Ontario, K1S 5B6, Canada
Evan Fishbein
Affiliation:
Department of Earth and Space Sciences, University of California, Los Angeles 90024
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Abstract

Currently some controversy exists in the micropaleontological community concerning the statistically correct number of counts required for quantitative examinations, particularly with respect to the effect of variations in the number of species between samples and the significance of varying fractional abundances on the reliability of results. This analysis of the various statistical methods used to determine the number of required counts has shown that the number of species has no relationship to the number of counts required to measure accurately fractional abundances. As part of the study, logarithmic contours plotting percentage abundance against the total number of specimens, which provide abundance errors at a 95 percent confidence level, have been generated. The plot is displayed logarithmically to emphasize the significance of rare microfossil elements that dominate most assemblages, and which are important in many paleoenvironmental studies. Based on the plot, it is recommended that researchers utilize counts of at least 50 for indicator species having a fractional abundance of approximately 50 percent or greater; 300 counts for species which comprise approximately 10 percent of a sample; 500–1,000 counts for species that make up 5 percent of a sample; and counts of several thousand for defining species that comprise 1 percent of a sample. It is important to note, however, that where similar biofacies are involved, higher counts are required to accurately distinguish them. It is also recommended that researchers include fractional error abundances with their estimated abundances to provide an indication of their accuracy.

Type
Research Article
Information
Journal of Paleontology , Volume 63 , Issue 2 , March 1989 , pp. 245 - 248
Copyright
Copyright © The Paleontological Society 

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References

Bhattachacharyya, G. K., and Johnson, R. A. 1977. Statistical Concepts and Methods. Wiley, New York, 639 p.Google Scholar
Buzas, M. A., Koch, S. J., Culver, S. J., and Sohl, N. F. 1982. On the distribution of species occurrence. Paleobiology, 8:142–150.Google Scholar
Dryden, A. L. 1931. Accuracy in percentage representation of heavy mineral frequency. Proceedings of the National Academy of Science, 17:233–238.Google Scholar
Phleger, F. B. 1960. Ecology and Distribution of Recent Foraminifera. John Hopkins Press, Baltimore, 297 p.Google Scholar
Schröder, C. J., Scott, D. B., and Medioli, F. S. 1987. Can smaller foraminifera be ignored in paleoenvironmental analyses? Journal of Foraminiferal Research, 17:101–105.CrossRefGoogle Scholar
Sen Gupta, B. K., Shin, I. C., and Wendler, S. T. 1988. Relevance of specimen size in distribution studies of deep-sea benthic foraminifera. Palaios, 2:332–338.CrossRefGoogle Scholar
Van Der Plas, L., and Tobi, A. C. 1965. A chart for judging the reliability of point counting results. American Journal of Science, 263:87–90.CrossRefGoogle Scholar
Wright, R. C., and Hay, W. W. 1971. The abundance and distribution of foraminifers in a back-reef environment, Molasses Reef, Florida. p. 121–174. In Jones, J. I. and Bock, W. D. (eds.), A Symposium of Recent South Florida Foraminifera. Miami Geological Society Memoir 1.Google Scholar