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frequency distribution for the following distributions:
Poisson, Poisson-binomial, Poisson with zeroes, negative
binomial, Neyman type A, and Thomas double Poisson.
The iterative solution technique of Bliss and Fisher
(1953) was used determining the parameter k of the negative
binomial. Common k values were calculated by the iterative
method (Formula 10) of Bliss and Owen (1958).
Results and Discussion
Data sets of counts of lepidopterous larvae fitted
the negative binomial or Poisson with zeroes better than
any other distribution (Table 5). Data sets obtained from
counts of fall armyworm and velvetbean caterpillar fit
the negative binomial significantly better than Poisson.
The percent fit of data sets to the negative binomial for
all larvae was relatively highi.e. 82-90% while similar
studies in soybeans by Shepard and Carner (1976) and in
cotton (Kuehl and Fye 1972) showed lower fits of negative
binomial for some of these same species. The Poisson
distributions fit the data fewer instances, 41-70% in every
case.
Values of common k for larvae were 3.93 for fall army-
worm, 5.20 for corn earworm, 7.27 for velvetbean caterpillar,
2.51 for granulate cutworm, and 3.58 for loopers. Only the
q
former 2 common k values significantly fit (P=0.05) a Tv
test for homogeneity of k in the different samples.