14
A. Kolmogoroff-Smirnoffs test on the
goodness of fit of population distributions.
###It is a powerful test and its use is
recommendable instead of classical chi-
square goodness of fit of population
distribution test.
###The test criterion compares the largest
absolute difference between cumulative
sample frequencies 7/ and population
distributions P[ with Kolmogoroff-
Smirnoffs extremal distribution critical
values, where the degrees of freedom are
the size of the samples:
H 0 :
P(KS v=n {a/ 2) < max17) - P\ < KS v=n ( 1 - a/2)) = 1-a
B-l ,###Kolmogoroff-Smirnoffs test on the
independence against interdependence.
###The same test performed for the goodness
of fit of population distributions can be
used to the test the independence against
interdependence. Indeed because the
goodness of fit hasn't limitations
concerning the dimension of domain of
population distributions, these could be
derived by multiplying marginal
frequencies.
###Thus comparing each multidimensional
frequency with the product of the
corresponding marginal frequencies, the
test on the independence against
interdependence is performed. The test
criterion is, obviously, the same explained
for the test on the goodness of fit of
population distributions, moreover because
the uniqueness of the test, its power is
conserved.
B-2. Modified Wilcoxon-Wilcox's test on
the independence against dependence (e.g.,
collinearity).
This test must be used instead of classical
Hotelling's test, when population
distributions aren't normal. It is a
generalisation of Spearman's rank test for
one Spearman's rank correlation
coefficient under the same hypotheses.
Let remember that the Spearman's rank
correlation coefficient is a function of the
sum of rank difference squares Df :
r s = 1—-
-1) /=1
I Df
where the ranks are assigned separately to
each component from the smallest
argument to the largest one and then
compared, element by element, in terms of
their difference. Furthermore when the null
hypothesis is the independence, the test
criterion compares the standardised value
of the Spearman's correlation coefficient
with the Student's t distribution critical
values, where the degrees of freedom are
the size of the sample minus two:
Therefore the modified Wilcoxon-Wilcox's
test on independence against dependence
(e.g., collinearity) requires for two separate
applications of a multiple test on a
quadratic combination of independent
Spearman's correlation coefficients. If the
answer is two times positive the null
hypothesis is accepted; on the contrary if
the answer is two times negative the null
hypothesis is rejected. Note that the third
case, where the null hypothesis is one time
accepted and another time rejected, or vice
versa, should be considered rare or, at
least, a priori known (e.g., the variables are
by physical or geometrical reasons, two by
two, correlated).
The test criterion compares the sums H
and K of standardised Spearman's rank
correlation coefficient squares with C-\
Fischer's F distribution critical values,
where the degrees of freedom are the
number of terms of the quadratic
combinations and the size of the samples
minus two:
H 0 :
. : (a/2)< H < F,
.A>
-«/2))=
Hq-
. : {al2)< K < F„
..»O-
-a ll))=
where: