Ecology of the burrowing amphipod, Pontoporeia affinis, in Lake Michigan / by Wayne Paul Alley.

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The geometric mean was used because it is a more conservative
estimate of the theoretical mean and is not affected by extreme values
to the same extent as the arithmetic mean. The geometric mean also
gives smaller counts relatively more importance than they enjoyed in
the computation of the arithmetic mean. The upper and lower limits
were calculated in the previously described manner because this method
eliminates the possibility of negative confidence intervals.
The correlation coefficient was employed as the second method of
analysis because it is a useful tool for measuring the degree of a relationship. The computer program written to compute the correlation
coefficient was also designed to present the relationship graphically.
The computer automatically rounded off the results in the construction
of the graph so these values are printed in regularly spaced columns
and rows. It is impossible to interpret the relative importance of these
data points because each point may actually represent more than one
value. These graphs merely show the trends of the relationships while
the correlation coefficients indicate the degree of the relationship.
The third method, that of multiple linear regression, is a useful
statistical tool in the study of biological systems because it has the ability
of mathematically removing the effects of confounding environmental
factors. Stepwise multiple regression analysis has the additional feature
of generating the multiple regression equation, variable by variable, in
the order of their relative importance.