This function pT.getSubTable allows access to the individual components
of a pension table. In contrast to a "normal" mortalityTable, which describes
probablilities for only mortality or a single population, a pension table
describes transition probabilities for other states, too:
active population (i.e. not disabled, not retired)
disabled population (occupational disability)
old-age pensioners
widows/widowers
pT.getSubTable(table, subtable = "qx")a pensionTable object
the key describing the desired subtable (see above for the full list)
The corresponding transition probabilities are:
mortality $q^a_x$ of actives (probability of death)
morbidity $i_x$ of actives (probability occupational disability)
mortality $q^i_x$ of disabled (probability of death)
reactivation $r_x$ of invalids (probability of becoming active again)
mortality $q^p_x$ of old-age pensioners
mortality $q^g_x$ of the whole population (including actives and disabled)
probability $h_x$ of leaving a widow/widower when dying at age $x$
average age $y(x)$ of surviving widow/widower when dying at age $x$
mortality $q^w_x$ of widows
The function pT.getSubTable extracts a single transition probability
from the pension table, using the keys given above. The returned object is
also a mortalityTable object.