Mortality risk calculations

Hi,

Has anyone else noticed on page 258 of Reading #17, Exhibit 43, that the Joint and Individual probabilities of 65-year-olds living beyond a certain age don’t seem to match what would ordinarily be expected if we simply calculated using the Male/Female figures?

Ie, probability of living to age 80 is given as 68% for Male, 80.6% for Female.  Here they list the Joint probability as 90.6%, though I would have thought it to be 93.8% (i.e., 32% probability male death x 19.4% probability female death = 6.2% probability both die before age 80, leaving 93.8% chance that at least one survives).

There could of course be some skew in the numbers if, for example, the probability of a spouse passing away increases if their partner dies (which anecdotally does seem to be the case).  Still, a 3.2% difference in results is fairly dramatic.

Does anyone have an idea as to why I might be wrong in my calculations?  The table in seems to have been provided by US Society of Actuaries.

Thanks in advance.