9597

• UCREFRP Catalog Number: 9597
• Author: U.S. Environmental Protection Agency.
• Title: Biological Field and Laboratory Methods for Measuring the Quality of Surface Waters and Effluents.
• USFW Year: 1973.
• USFW - Doc Type: Cincinnati, OH.
• Copyright Material: NO

.

t

BIOMETRICS - LINEAR CORRELA nON

If a correlation coefficient is computed and is
of low magnitude, test it to determine whether
it is significantly different from zero. The test, a
t-test, is computed as follows:

The computed t is compared with the tabular t
with n- 2 degrees of freedom and chosen proba-
bility level. If the computed t exceeds the
tabular t, the null hypothesis that the true corre-
lation coefficient equals zero is rejected, and the
computed r may be used.

t =
~(l-r2)
(n-2)

(49)

8.0 BIBLIOGRAPHY

Cochran, W. G. 1959. Sampling techniques. Jolm Wiley and Sons, New York. 330 pp.
Li, J. C. R. 1957. Introduction to statistical inference. Edward Brothers, Inc., Ann Arbor. 553 pp.
Natrella, M. G. 1963. Experimental statistics. National Bureau of Standards Handbook No. 91, U.S. Govt. Printing Office.
Snedecor, G. W., and W. G. Cochran. 1967. Statistical methods, 6th edition. Iowa State Univ. Press, Ames.
Southwood, R. T. E. 1966. Ecological methods with particular reference to the study of insect populations. Chapman and Hall, Ltd.,
London. 391 pp.
Steele, R. G. D., and J. H. Tonie. 1960. Principles and procedures of statistics with special reference to the biological sciences. McGraw
Hill, New York. 481 pp.
Stuart, A. 1962. Basic ideas of scientific sampling. ~fafner, New York. 99 pp.

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