Forecast Models

[Former Member]

Hi Guys

Can any bdy explain, how the Initialization values of Basic ,Trend,Seasonal ,Ex-post and MAD caluclates in the Seasonal model.how the values are caluclated after initializing period(Basic ,Trend,Seasonal ,Ex-post and MAD )

Thanks in advance

Ravi Pradeep P

rpr.pulusu@gmail.com

[somnath_manna · Accepted solution]

Hi Pradeep,

Please look at the following presentations/docuements under BPX Community >> Supply Chain Management >> Demand Planning

Forecasting Workshop

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/7a4025f8-0a01-0010-0fb2-b7a...

Slies 16-18 explain how calculation for Trend model is done in Initialisation, Expost and Forecast Horizon. The computation logic just changes from model to model which are detailed in later slides.

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/2bb941f8-0a01-0010-88a6-ee8...

Data Analysis and Statistical Model Selection

This document may not give you direct answers to your questions but worth going through.

Hope these help.

Thanks,

Somnath

[Former Member · Accepted solution]

Hi Sommanth,

Thanks for your reply, i all ready gone through that and caluclating the Basic,Seasonal,Trend ,Expost and MAD values with the system. But problem is for Trend,

Basic value = Mean of the historical values of the first historical season

Trend value = 0

Seasonal index for a period = Historical value for that period divided by the basic value

Mean absolute deviation (MAD) = 0

These are the formulas in Trend Model. I am using Outlier correction for this we required Tolerance Threshold value(T) i.e T=Sigma*MAD, but in Trend model MAD = 0.

Can you please tell me these formulas are correct??????

Thanks in advance

Regards

Pradeep

[somnath_manna · Accepted solution]

Hi Pradeep,

I need to understand the values you have mentioned.

Are you saying that your trend value is zero in the ex-post period. In that case why do you want to consider a Trend model.

Also how can your MAD be zero. I am not sure if these are the typical values for a Trend Model.

Of course if your MAD is zero (which I doubt) then the tolerance threshold value will be same as the ex-post forecast and outlier correction will not happen.

Please check your formulae for trend.

Thanks,

Somnath

[Former Member]

Hi Guys,

I have a problem, i'm using a trend model and my question is how SAP initialize the forecast with 12 Value.

It's clear by previous document how it's work with 3 value:

Hist3-Hist1

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2

But my question is:

How it work with 3, 4, 5....12 value?

Thank you very much for your help!