The statistical distribution was developed starting from the values approximated 
to the nearest metre, contained in the general table. The relative percentile frequencies 
were calculated in respect to the total number of control points contained in the 
different tests for each coordinate. This number is written in the same table, in 
special columns. The percentile values of the frequencies are calculated with only one 
decimal figure. 
The last two groups of rows contain the number of points that have not been 
plotted in the different tests, and the number of control points used for adjustment 
of the blocks, respectively. 
We consider the values of the mean and of the variance of these statistical variables 
scarcely significant, therefore they have not been written in table. 
The analysis of table 2 permits an immediate view of the asymmetry of some 
blocks in respect to the 0. In this connection it is useful to consider the 5 central 
classes of frequency, included within — 15 and -f 15 m. The remaining classes of 
frequency are, in fact, much more influenced by anomalous points, namely by the 
points with errors in the coordinates much higher than the average and due to excep 
tional reasons. 
First of all, one can note that the percentage of the errors equal to 0 is in correla 
tion with the number of points used for the blocks adjustment. This number is ranging 
from 3,1% in the X for test 11, to 24,7% in the Y for test 18. Test 11, in fact, was 
adjusted with only 4 points in planimetry, while test 18 was adjusted with 38 points. 
This statistical table of errors appears very significant as it permits more imme 
diate comparisons among the results of the tests. That is, a comparison may be made 
between those tests obtained by adjusting in different ways the same measures, or 
those tests obtained from measures executed with different instruments and photo 
graphic material, but adjusted on the same control points and by the use of the same 
computational procedures. 
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