Contents Telektronikk - Telenor

Registered number of calls
Registered number of calls
126
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23>24
Minutes
Figure 8 Call holding times, Period 1, Interval 2
Number of observations: 8433 Mean: 4.93 mins
Standard deviation: 15.04 mins Maximum holding time: 600.0 mins
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23>24
Minutes
Figure 9 Call holding times, Period 1, Interval 3
Number of observations: 2799 Mean: 4.49 mins
Standard deviation: 14.11 mins Maximum holding time: 518.9 mins
holding time of 600 min. – see footnote
after Table 7) contributes to 13 % increase
in the coefficient of variation and
4 % increase in the mean alone.
However, the results still indicate clearly
that standard deviation is larger than
mean in nearly every category, which
confirms that the distributions of holding
times do not follow negative exponential
distributions.
Table 7 also shows that in contrast to
Interval 1, the mean holding time had
been reduced by 4.7 % from Period 1 to
Period 2 (from 4.93 min. down to 4.70
min.).
When comparing the results from Interval
1 with that from Interval 2, we observed
that both means and coefficients
of variation are larger (in some cases
considerably) outside the normal working
hours than that during working hours.
Another observation we made is that
among the “normal” domestic calls (i.e.
the categories of Local, Neighboring
counties, and Long distance calls) the
distance plays an important role – the
longer the distance is, the longer is mean
call holding time. We believe that the
reason for this is that users appear to pay
more attention to the price when they
make more expensive calls, so they
choose to make long calls when the price
is lower.
3.5.3 Interval 3: Weekends
In Interval 3 both the call intensity and
the number of calls are lower than that in
Interval 2.
The distribution of call holding times for
all outgoing calls (Interval 3, Period 1) is
shown in Figure 9.
Figure 9 looks similar to that of Figure 8
(Interval 2). The mean holding time is
much longer than that in Interval 1, but a
bit shorter than that in Interval 2.
Table 8 shows the number of observations,
mean holding times, standard deviations,
coefficients of variation, and maximum
holding times for all successful
outgoing calls and for each category, for
both observation periods.
3.5.4 Comparisons and discussions
The registered holding times show that
the mean holding time for all calls is considerably
longer outside normal working
hours. The most significant differences
appear on longer distance calls (calls to
neighbouring counties, long distance calls