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(a) Population size in time
(b) Inflow fitted with birth rates
Fig. 4.
Demographics
subgroups HPVw and StageII, who can still develop cancer until their death
caused by any other factors (natural death). Life expectancy of those women is
growing according to Statistics Polland - GUS [5] and it is modeled as linear
increase for the whole time horizon of simulation. All agents could leave sys-
tem due to natural death rate which is a function of population size, age and
sex. Inflow to the system are the young of age 15 (respectively more boys than
girls according to GUS). We can extrapolate number of the young coming into
the system for the next 15 years of simulation (until 2027) by scaling number
of young Poles who will grow up and start their sexual life in future. We can
observe two characteristics of Poland - wave structure, and birth rate is mainly
decreasing (Figure 4(b)). In effect population is aging and dying out. After the
pick year in the number of the young coming into the system, which is around
2035, this number would probably decrease (as it can be observed in first years
after pick). We decided not to follow this prediction, and following the rule to
be as much conservative as possible, the rates of coming in later years (after
2035) are assumed constant. In effect, Polish sexually active population (corre-
sponding to workers age span) will decrease from 27
.
5 in 2013 to 23
.
5 million in
2039 (Figure 4(a)). This value alone should alarm the authorities, and probably
it is overestimated, since emigration of Polish citizens has not been taken into
account.
Transition.
Transition of disease can take place due to sexual contact, with
given probability. It has been estimated in other paper between 0
.
4to0
.
6, so
we choose it as 0
.
5. With respect to Finish data set, individuals in our model
have a randomly chosen number of new contacts each day, which follows the
empirical distribution for given age groups from the Finish surveys (rescaled
to Poland). Stochasticity was introduced not at the level of individuals, but at
the level of subgroup (limitation of Vensim). One can understand that all people
