jimmy comments on Rational Romantic Relationships, Part 1: Relationship Styles and Attraction Basics - Less Wrong

48 Post author: lukeprog 05 November 2011 11:06AM

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Comment author: DanielVarga 06 November 2011 04:55:08PM 1 point [-]

Obviously, I agree. But let me ask: for what values of X would you choose X$ with 15% chance instead of 1,000,000,000$ with 100% chance?

A quite extreme, but still somewhat defensible theoretical assumption is that utility is logarithmic in money. I once heard Bernoulli already worked with this assumption, many hundred years before Neumann-Morgenstern, and it is probably not so silly to assume this near the power-law tail of the wealth distribution. Not that I think it means anything, but from this admittedly extreme starting point, we get that lg(500) = 2.7 is three times as useful as 0.15*lg(1000000) = 0.9.

Comment author: Luke_A_Somers 06 November 2011 08:02:17PM *  7 points [-]

That assumes someone who initially has $1, and in that case it's certainly true. If on the other hand you initially have, say, $10k...

log(10.5k) - log(10k) ≈ 0.02

0.15 * (log(1.01M) - log(10k)) ≈ 0.3

The crossover point based on this system is $191. Less than that, and you do better with $500. More than that, and you'd try for the million.

Comment author: jimmy 07 November 2011 07:14:00PM *  1 point [-]

That's not quite right in practice either. Even if you took all my money, I'd still take the 15% chance at $1M and maybe sell a 15% chance of $5k for $500.

Or if that is somehow not allowed, then I'd run into a bit of debt until my next pay check. Even if I really was spending all the money I make and averaging $0, $500 is a mere blip in the noise, not a factor of infinity more money.

It makes more sense to look at the total money in over whatever time scale you plan for.

Comment author: Luke_A_Somers 08 November 2011 02:27:01PM *  0 points [-]

Yeah, the prospect of other incomes makes a big difference. I neglected to include a requirement that the initial amount, whichever value it takes, is as much as you can come up with before you'll be needing money again.

Comment author: Michael_Sullivan 27 November 2011 04:37:34AM 0 points [-]

The present value of my expected future income stream from normal labor, plus my current estimated net worth is what I use when I do these calculations for myself as a business owner considering highly risky investments.

For most people with decent social capital (almost anyone middle class in a rich country), the minimum base number in typical situations should be something >200kUS$ even for those near bankruptcy.

Obviously, this does not cover non-typical situations involving extremely important time-sensitive opportunities requiring more cash than you can raise on short notice (such as the classic life-saving medical treatment required).