  We studied the complete randomness of the angular distribution of gamma-ray
bursts (GRBs) detected by BATSE. Since GRBs seem to be a mixture of objects of
different physical nature we divided the BATSE sample into 5 subsamples
(short1, short2, intermediate, long1, long2) based on their durations and peak
fluxes and studied the angular distributions separately. We used three methods,
Voronoi tesselation, minimal spanning tree and multifractal spectra to search
for non-randomness in the subsamples. To investigate the eventual
non-randomness in the subsamples we defined 13 test-variables (9 from the
Voronoi tesselation, 3 from the minimal spanning tree and one from the
multifractal spectrum). Assuming that the point patterns obtained from the
BATSE subsamples are fully random we made Monte Carlo simulations taking into
account the BATSE's sky-exposure function. The MC simulations enabled us to
test the null hypothesis i.e. that the angular distributions are fully random.
We tested the randomness by binomial test and introducing squared Euclidean
distances in the parameter space of the test-variables. We concluded that the
short1, short2 groups deviate significantly (99.90%, 99.98%) from the fully
randomness in the distribution of the squared Euclidean distances but it is not
the case at the long samples. At the intermediate group the squared Euclidean
distances also give significant deviation (98.51%).
