Help with Corrected History.

[Former Member]

Hello friends,

I am pasting a portion of text which I am not able to understand.If any of you can help me understand it I would be very thankful.

This is about Automatic Adjustment of corrected history.

If no forecasts have been made for a long time, you can use automatic adjustment

of corrected history key figure.

"For periods where there is no corrected history in the database, the system uses

the original history. It is July 1 and you have not created any forecasts over the

past two months. The corrected history from the previous two months contains

manual corrections that you do not want to lose. For this reason, your corrected

history does not contain values for May or June. If the system were to base the

forecast on the historical values, the forecast results would be inaccurate because

of the zero values from May and June. To prevent such inaccuracies, you set the

automatic adjustment of corrected history key figure. The system then uses the

original historical values for May and June."

What I do not understand is, if corrected history from the prev 2 months has manually corrected data that cannot be lost, then how does it mean that corrected history does not contain any values for those 2 months.Sounds pretty contradictory to me.

If Experts can help me with this

Thanks guys..

Take care..

[Former Member · Accepted solution]

Hi Amit.

It looks like your F1 is from an earlier version.

SCM 5.0 F1 looks like this, which I think explains it a bit more clearly:

Automatic Adjustment of Corrected History

Allows you to base your forecast on the key figure Corrected history even if no forecast has been carried out for some time.

In periods for which no corrected history exists on the database, the system substitutes the original history.

Example

It is the 1st of July and you have not carried out a forecast for two months. The corrected history you used two months ago contains some manual adjustments that you do not want to lose. Your corrected history now looks like this:

Jan Feb March April May June

500 514 520 524 0 0

If the system based the forecast on these historical values, the zeros in May and June would distort the forecast results.

To prevent this distortion, you set the indicator Adjust corrected history. The system then substitutes the original history values in May and June.

Dependencies

You can use this option if you have also selected Read corrected history data from planning version in the univariate forecast profile.

You define the key figure in which corrected history is saved in Customizing for Demand Planning.

hope this helps.

I can explain it more if you like.

regards, Mark.

[Former Member · Accepted solution]

Hi Mark,

Thanks for the reply but I still do not understand why if there has not been forecasting in the past 2 months, the corrected history should be zero. Is corrected history not the correction put on the (for eg. )actual sales in the past months. So if there is no 'forecasting' in the past 2 months, it does not mean nothing was sold. There must still be some amount of sales which should be corrected in the ' Corrected history' key figure.

"

The corrected history you used two months ago contains some manual adjustments that you do not want to lose. Your corrected history now looks like this:

Jan Feb March April May June

500 514 520 524 0 0

"

What does this mean? Why are there zeros there?

I am sorry but I am kind of slow in understanding this, I just began.

Please Enlighten Me.:)

Thanks a lot for the earlier reply.

[Former Member · Accepted solution]

Hi Amit,

It doesnot mean that the history is not taken into account. Infact as the history is zero, lets say, then the system considers the history entered in the corrected history key figure.

As the history in the past two months is zero and if you have a pattern till then, as the forecasting is nothing but joining history points to predict the future points, it is changing the way the curve goes. That's what outliers correction meant...

Hope this helps.

[Former Member · Accepted solution]

Thanks for the reply Visu, I know it replaces the corrected history with original values if corrected history has zeros,but what I do not understand is, why is the corrected history zero? How can it be zero unless, the original history is also zero.In that case, replacing the corrected history by original history will make no sense as both will be zeros.

When they say," assume there was no forecast in the past 2 months".They draw a conclusion that the corrected history for those months is zero. I am not able to understand this conclusion which they draw. May be I am not understanding the language well..

Please help.

[Former Member · Accepted solution]

Hi Amit.

Ok, I'll try and explain.

First of all, this function can only be used if you have set the "Read Corr. History Data from Planning Version" first. Remember, <b>the Corrected history is the first stage in the forecast "calculation" by the system</b>. This setting specifies that you have stored the corrected history from previous forecasting activity and you want to use this "corrected history"as a history basis, not the actual history.

However, if you have not done forecasting on this selection for a while there will be a gap in the "corrected history" from the last time you ran a forecast. The setting "Adjust Corrected History" looks out for this situation and will substitute actual history if this is the case.

This would mean that the two zero's in the example TS will be replaced by actual history for the purposes of forecasting.

It's complicated I know and is only of use if you are storing and using the corrected history.

Hope this helps, Mark.

[Former Member · Accepted solution]

Thanks Mark,

Just to reconfirm. The system just works this way,it says, if you are not going to forecast anything in May and june,I am not going to calculate the corrected history for it. No unnecessary calculations and hence it puts zeroes there.

It answers my question.Full points to you.

Thanks a lot.

[Former Member]

I think when you correct the history manually it is stored in another key figure called " Adjusted History" which is taken into account while calculating the Final history for that key figure.

Having another key figure in the picture explains why the corrected history key figure stays blank when there is manual correction on the actual history.

After answering my own question I feel kinda stupid. But If someone can counter of confirm my logic it would be great.