RE: SIP vs ROI

Kent wrote:

>At the end of Critical Chain, Goldratt suggests measuring investment in 
>"dollar days", the number of dollars times the number of days those 
>dollars are unavailable for other uses. He doesn't explain in any more 
>detail, though. Does anyone know what he's talking about?

Goldratt is reinventing the bookkeeping wheel, without having studied the 
original. The basis of bookkeeping is to isolate whatever you wish to 
measure by posting the transactions you wish to measure in an account, or 
group of accounts. Once isolated, the value of change in the account, or 
accounts, is measured in relation to a universal medium of exchange. Money 
works nicely for that purpose. Time would work too, if you had no reason to 
care about comparative value.

Dan