QUERY Age of material in a stock
Posted: Fri Apr 13, 2007 12:12 pm
Posted by Richard Dudley <richard.dudley@attglobal.net>
Little's law can tell us about the length of time material is in a stock when the stock is in equilibrium.
Is there any way to _estimate_ the the length of time material is in a stock
when that stock is not in equilibrium? Or is this a complete unknown?
[ For those who don't recognize it - as I didn't - Little's law is simply
stock = average delivery delay * inflow
which I tend to think of as Jay's formulation that
average delivery delay = stock / outflow
where outflow = inflow in steady state. Jay's formulation is always
exactly true if the underlying delay distribution is exponential
(outflow = level/delay) - if not then only in equilibrium just like
Little's Law.]
Richard
____________________________
Richard G. DudleyPosted by Richard Dudley <richard.dudley@attglobal.net> posting date Fri, 13 Apr 2007 14:20:06 +0700 _______________________________________________
Little's law can tell us about the length of time material is in a stock when the stock is in equilibrium.
Is there any way to _estimate_ the the length of time material is in a stock
when that stock is not in equilibrium? Or is this a complete unknown?
[ For those who don't recognize it - as I didn't - Little's law is simply
stock = average delivery delay * inflow
which I tend to think of as Jay's formulation that
average delivery delay = stock / outflow
where outflow = inflow in steady state. Jay's formulation is always
exactly true if the underlying delay distribution is exponential
(outflow = level/delay) - if not then only in equilibrium just like
Little's Law.]
Richard
____________________________
Richard G. DudleyPosted by Richard Dudley <richard.dudley@attglobal.net> posting date Fri, 13 Apr 2007 14:20:06 +0700 _______________________________________________