Forecast or What?

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baleceka
Junior Member
Posts: 5
Joined: Thu Sep 12, 2019 11:14 pm
Vensim version: PLE

Forecast or What?

Post by baleceka » Fri Oct 18, 2019 12:18 pm

Hello guys

I have a time series of data as follows:
year production
2000 7085
2001 8680
2002 9409
2003 11365
2004 14361
2005 13682
2006 14303
2007 14845
2008 15526
2009 16262
2010 20779
2011 20983
2012 22967
2013 24499
2014 24913
2015 25546
2016 28720
2017 31640
2018 33681


I want to perform a forecast from 2019 to 2025. Which one should I do?
1. Should I use forecasting method as https://www.vensim.com/documentation/fn_forecast.htm? How to do so?
2. Or should I just apply a stock-flow mode (production as stock, and the rate will be calculated using excel)?
3. Or is there any other way to do so?


Thank you guys!

Administrator
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Posts: 3423
Joined: Wed Mar 05, 2003 3:10 am

Re: Forecast or What?

Post by Administrator » Fri Oct 18, 2019 12:22 pm

It's up to you what method you use. Given you are using PLE, the only way for you to get this data into Vensim is via a lookup table, so you can either use the forecast function or LOOKUP EXTRAPOLATE. But if you are more comfortable doing the forecast in Excel, you can do it there instead.
Advice to posters seeking help (it really helps us to help you)
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tomfid
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Joined: Wed May 24, 2006 4:54 am

Re: Forecast or What?

Post by tomfid » Fri Oct 18, 2019 3:57 pm

The FORECAST function is just trend-extrapolation, which is sometimes useful but often pretty dumb.

A more sophisticated approach would be to build a model that captures the driving forces for production, and fit the model to this data (by hand or by optimization). Then the model generates the forecast.

If this is just a small part of a larger system, the forecast function might be fine (and realistic, if managers forecast simplistically).

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