what is Forocst function means

[sally]

hi,,

i want to use a function to do the forecasting----moving average. can i use Forcst function to do this?

[bob@vensim.com]

It is worth reading Sterman's book on this - the standard representation of expectations as formed by people is a SMOOTH function which is an exponentially weighted moving average.

[sally]

if i only want to use simple moving agreage ?

which fuction should i use?

thank you .

[bob@vensim.com]

To get a simple moving aveage use

moving average = period accumulation/averaging time
period accumulation = INTEG(value to average - outflow,init average value*averaging time)
outflow = DELAY FIXED(value to average,averaging time,init average value/averaging time)

[sally]

i am still confused about the forecasting function in vensim, i want to use the customer to forecasting the inventory level.

i want to use simple moving average ,,

hope some one can help me to figure it out..

thank you

[sally]

i still didn't know how to set up the forecast?

hope some one can help me

[bob@vensim.com]

use

expected demand = SMOOTH(demand,time to form expectations) ~ Widget/Month
Time to form expectations = 5 ~ Month

Expected Inventory = MAX(0,Inventory + (expected production - expected demand) * Inventory Forecast Horizon) ~ Widget
Inventory Forecast Horizon = 4 ~ Month