Ch. 13 Multiple Decrements

Discussion in 'CT5' started by nmellor, Feb 23, 2009.

  1. nmellor

    nmellor Member

    Hi

    I am just a bit confused by two points of the theory in Chapter 13:

    - On page 8 it says the expected number of additional decrements from cause k in (x,x+1) is 1/2 * (ad)^-k * q^k. How is this obtained?

    - On page 14 it says q^alpha = t_p^alpha * mu^alpha. Surely the inital rate of mortality is the sum of the RHS over all values of t from 0 to 1?

    If you could help that would be appreciated.

    Many thanks

    Nick
     
  2. John Potter

    John Potter ActEd Tutor Staff Member

    Hi Nick,

    Anyone who leaves due to decrement other than k does so, on average halfway through the year. Bring these people back and then apply a qk to them.

    You're right on your second point but the LHS is already in an integral between t=0 and t = 1 above. The CR is saying we can take these two terms as a constant outside the integral because the decrements are uniformly distributed,

    Good luck!
    John
     

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