Hello, I cant seem to derive the f(dx)=0.0888 where dx =20. qx=-9.05+0.08x q(80)=-9.05+0.08(80)=-2.53 How can qx be greater than 1? Is the text missing out something? Can anyone derive f(dx) where dx=20?
Hi Alex This is a good question, had to stare at it for a while before the penny finally dropped! The model for qx is a log-linear function of age. Therefore: ln qx = a + bx qx = exp(a+bx) With x = 80, a = -9.05 and b = 0.0815, I get qx = 0.079659. Then yx = qx * lx = 0.079659 * 250 = 19.91476. And f(dx) = [exp(-19.91476) * 19.91476^20]/20! = 0.0888 This is a type of generalised linear model from CT6. Hope this helps Anna
