Ventana software support forum

The discussion on time allocation is most interesting...I am currently
concerned with modelling personal time allocation (at least, managerial
time allocation from an individuals rather than a firms point of view)
- any tips gratefully received. Thanks to Kevin Agastein, Jim Hines,
George Richardson and John Sterman (especially the second point)
for their comments which help me too. However, do we
not need to make clear that it is frequently effort we are modelling and
not Father Time per se? I think this is partly what Steve Roderic was
asking when he posed the question.

It is a slightly tricky issue when raised by students on programmes
using the Dynamic Resource System View (Warren, Morecroft) since,
resource we define, in short, as something useful to an organisation, which
accumulates and depletes over time, and to
which is has access. Time sometimes causes confusion. "Time is a
limited resource" is a common expression, "Im short of time", "Time is
running out" etc. but my stock answer (pun intended) is that Time is not
a resource concept but the path along which our dynamic analysis plays
out. When we represent Time in our models, other than as the basis for
sequential differential calculation, we are, in fact, modelling
something more tangible than temporal. Is this a moot or even
significant point?

The most practical way we have found of treating it for managerial
audiences is as follows:
- the total time available may reflect a stock (e.g. number of sales
people, number and capacity of machinery),
- the consequence of time allocation is often an accumulation of other
resources (e.g. 20 sales people with 40 hours/week = 800 hours, of which
150 are devoted to winning new customers, who are won at the rate of 1 per
10 hours effort = 15 new customers/week, or 5 machines producing 20 units
per hour = 100 units of total output, of which 35 are devoted to product A,
so inventory of A rises at 35/hour)
The same concept seems to work for most folk when thinking about their own
time - I have 70 hours per week to produce useful stuff, of which 5 are
devoted to answering SD listserve questions, which I can do at the rate of
2 pr hour, so my accumulated output of replies is rising at 10/week (a gross
exageration!).
In none of these cases is time accumulating or depleting.

It is of course easy to conceive of this time-allocation process as a
zero-sum game
stock and flow model - in scenario modelling of media consumption, we have
conceived of consumers having e.g. 10hours/week of time available for
consuming infotainment, of which they may allocated 2 to newspapers, 3 to
TV, 2 to cinema, etc. Then the extent to which each service provides a
good use of time (dimensionless 0-1), time is dragged from one use to
another. Time-as-a-stock is useful in this case because of the stickiness
of the flow.

The only useful exception we have found is when a firms actual output is
hours of something - e.g. the BBC produces X hours per month of
transittable content, which is added to its library of total content-hours,
i.e. if you sat down today to play every minute of every tape in that
library, it would last Y hours (or decades!)

Happy new year everyone.

Rod.

Roderick Brown

Home Office: +44 (0)1553 631 516
e-mail: rod@strategydynamics.com

Global Strategy Dynamics Limited