Creeping Incrementalism
Member
I was thinking about upgrading my year-by-year NRA membership to lifetime, and out of curiosity decided to calculate the present value of renewing yearly.
The result: I would save about $400 by renewing year by year.
Assuming: (1) I die at the same age as my maternal grandfather (paternal is still alive), and (2) an interest rate of 10%, and
using the formula for present value (PV) of an annuity, PV=((1-((1+r)^(-t)))/r)*p
where p is the yearly membership payment of $35, r is the interest rate of 10% (which I think is an orthodox approximation of long term return for the stock market), and t = 69 years (years until I die--I think I'm younger than a lot of people here and my ancestors tend to live a long time),
PV = $349.51, which is $400.49 less than the $750 lifetime membership fee.
Did I do my math right? Isn't the point of paying for a lifetime membership to end up paying less?
The result: I would save about $400 by renewing year by year.
Assuming: (1) I die at the same age as my maternal grandfather (paternal is still alive), and (2) an interest rate of 10%, and
using the formula for present value (PV) of an annuity, PV=((1-((1+r)^(-t)))/r)*p
where p is the yearly membership payment of $35, r is the interest rate of 10% (which I think is an orthodox approximation of long term return for the stock market), and t = 69 years (years until I die--I think I'm younger than a lot of people here and my ancestors tend to live a long time),
PV = $349.51, which is $400.49 less than the $750 lifetime membership fee.
Did I do my math right? Isn't the point of paying for a lifetime membership to end up paying less?