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  • #53294

    Itsme
    Participant

    Hi,
    I tried to forecast volume inflows for 4 months and used the Time series decomposition method. The forecast starts from the month leaving one behind.
    E.g: The data was till Dec’09 and the forecast results started from Feb 2010. Can you explain me why this happens?
    Itsme

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    #189496

    Mikel
    Member

    Defective end user?

    0
    #189500

    Russell Demetri Ollie Sr.
    Participant

    Decomp method is typically used for long time periods where you have seasonality components observed in your data.
    What tool are you using (Minitab, JMP, etc.)? What’s the resolution of your data (daily, weekly, etc.)?

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    #189583

    Itsme
    Participant

    I am using Minitab15 and the forecast is a monthly one.
     
    Thanks

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    #189585

    Russell Demetri Ollie Sr.
    Participant

    OK, so if I understand you correctly then you only have 4 data points?  In this case decomposition is not ideal since it is for long periods that reflect seasonality and you won’t see that with 4 months of monthly data.
    I think the options for you are going to be moving average or single exponential smoothing (until you get enough data for seasonal effects and then you might try double exp smoothing or Winters exp smoothing.)  These are all in MiniTab 15. 
    Your question reminded me I just inherited a new green belt candidate who is going to do a forecasting project (has several years of weekly data) and I haven’t played with a Kalman filter in ages so I’ve got to brush up a bit (don’t recall if I can even do a Kalman in Minitab – I know I couldn’t back in 13.x and used specialized software for it years ago.)

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    #189592

    MBBinWI
    Participant

    You need a better tool.  Try the Predictor module in CrystalBall from Oracle.  It is set up to do exactly what you are trying to do and is pretty easy (with the new wizard) to set up and use.  You can even get a full function 30 day demo license. 

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    #189610

    Itsme
    Participant

    No, I have 12 months data and I have to forecast for 12 more months… The problem is when I try it in Minitab15, the date range I give is Jan-Dec09. However, in decomposition method, the forecast shows from Feb 2010 instead of Jan 2010. There is no forecast for Jan. Please clarify…

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