stretching a forecast

M

MartinL

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Joined
Oct 16, 2008
Messages
1,141
Office Version
  1. 365
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  1. Windows
Sorry for the lousy title
I have had a request from a different team to see if I could solve a problem for them....I cant.
So I am turning to my friends here to see if you have an ideas.

Basically we have a 13 week promotion table[Col A]
That shows the consumer take up as a percentage [Col B]

What is needed is the percentages stretched out over 17 weeks
How on earth can I even start looking at this as a best guess.

Percentages for this task can be to 4 decimal places I have shown 0dp just for ease of writing this.
[TABLE="class: grid, width: 200, align: left"]
<tbody>[TR]
[TD]Week[/TD]
[TD]%Current[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]1%[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]4%[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]4%[/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD]6%[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]10%[/TD]
[/TR]
[TR]
[TD]6[/TD]
[TD]12%[/TD]
[/TR]
[TR]
[TD]7[/TD]
[TD]12%[/TD]
[/TR]
[TR]
[TD]8[/TD]
[TD]20%[/TD]
[/TR]
[TR]
[TD]9[/TD]
[TD]18%[/TD]
[/TR]
[TR]
[TD]10[/TD]
[TD]9%[/TD]
[/TR]
[TR]
[TD]11[/TD]
[TD]2%[/TD]
[/TR]
[TR]
[TD]12[/TD]
[TD]1%[/TD]
[/TR]
[TR]
[TD]13[/TD]
[TD]1%[/TD]
[/TR]
[TR]
[TD]14[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]15[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]16[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]17[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]
 

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I would do the following.

[TABLE="class: grid, width: 700"]
<tbody>[TR]
[TD][/TD]
[TD="align: center"]A
[/TD]
[TD="align: center"]B
[/TD]
[TD="align: center"]C
[/TD]
[TD="align: center"]D
[/TD]
[TD="align: center"]E
[/TD]
[TD="align: center"]F
[/TD]
[TD="align: center"]G
[/TD]
[TD="align: center"]H
[/TD]
[TD="align: center"]I
[/TD]
[TD="align: center"]J
[/TD]
[TD="align: center"]K
[/TD]
[/TR]
[TR]
[TD]1
[/TD]
[TD="colspan: 2"]
Orig Distrib​
[/TD]
[TD="align: center"][/TD]
[TD="colspan: 3"]
Orig Lookup Table​
[/TD]
[TD="align: center"][/TD]
[TD="colspan: 4"]
New Distrib​
[/TD]
[/TR]
[TR]
[TD]2
[/TD]
[TD]
Wk#​
[/TD]
[TD]
Distrib​
[/TD]
[TD="align: right"][/TD]
[TD]
Table#​
[/TD]
[TD]
Cuml Distrib​
[/TD]
[TD]
New Wk#​
[/TD]
[TD="align: right"][/TD]
[TD]
Wk#​
[/TD]
[TD]
Distrib​
[/TD]
[TD]
Cuml Distrib​
[/TD]
[TD]
Orig Table#​
[/TD]
[/TR]
[TR]
[TD]3
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]1
[/TD]
[TD="align: right"]0.0000%
[/TD]
[TD="align: right"]0.0000
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: right"]
4​
[/TD]
[TD="align: right"]1
[/TD]
[TD="align: right"]1.0000%
[/TD]
[TD][/TD]
[TD="align: right"]2
[/TD]
[TD="align: right"]1.0000%
[/TD]
[TD="align: right"]1.3077
[/TD]
[TD][/TD]
[TD="align: right"]1
[/TD]
[TD="align: right"]0.7647%
[/TD]
[TD="align: right"]0.7647%
[/TD]
[TD="align: right"]1
[/TD]
[/TR]
[TR]
[TD="align: right"]
5​
[/TD]
[TD="align: right"]2
[/TD]
[TD="align: right"]4.0000%
[/TD]
[TD][/TD]
[TD="align: right"]3
[/TD]
[TD="align: right"]5.0000%
[/TD]
[TD="align: right"]2.6154
[/TD]
[TD][/TD]
[TD="align: right"]2
[/TD]
[TD="align: right"]2.3529%
[/TD]
[TD="align: right"]3.1176%
[/TD]
[TD="align: right"]2
[/TD]
[/TR]
[TR]
[TD="align: right"]
6​
[/TD]
[TD="align: right"]3
[/TD]
[TD="align: right"]4.0000%
[/TD]
[TD][/TD]
[TD="align: right"]4
[/TD]
[TD="align: right"]9.0000%
[/TD]
[TD="align: right"]3.9231
[/TD]
[TD][/TD]
[TD="align: right"]3
[/TD]
[TD="align: right"]3.0589%
[/TD]
[TD="align: right"]6.1765%
[/TD]
[TD="align: right"]3
[/TD]
[/TR]
[TR]
[TD="align: right"]
7​
[/TD]
[TD="align: right"]4
[/TD]
[TD="align: right"]6.0000%
[/TD]
[TD][/TD]
[TD="align: right"]5
[/TD]
[TD="align: right"]15.0000%
[/TD]
[TD="align: right"]5.2308
[/TD]
[TD][/TD]
[TD="align: right"]4
[/TD]
[TD="align: right"]3.1764%
[/TD]
[TD="align: right"]9.3529%
[/TD]
[TD="align: right"]4
[/TD]
[/TR]
[TR]
[TD="align: right"]
8​
[/TD]
[TD="align: right"]5
[/TD]
[TD="align: right"]10.0000%
[/TD]
[TD][/TD]
[TD="align: right"]6
[/TD]
[TD="align: right"]25.0000%
[/TD]
[TD="align: right"]6.5385
[/TD]
[TD][/TD]
[TD="align: right"]5
[/TD]
[TD="align: right"]4.5883%
[/TD]
[TD="align: right"]13.9412%
[/TD]
[TD="align: right"]4
[/TD]
[/TR]
[TR]
[TD="align: right"]
9​
[/TD]
[TD="align: right"]6
[/TD]
[TD="align: right"]12.0000%
[/TD]
[TD][/TD]
[TD="align: right"]7
[/TD]
[TD="align: right"]37.0000%
[/TD]
[TD="align: right"]7.8462
[/TD]
[TD][/TD]
[TD="align: right"]6
[/TD]
[TD="align: right"]6.9412%
[/TD]
[TD="align: right"]20.8824%
[/TD]
[TD="align: right"]5
[/TD]
[/TR]
[TR]
[TD="align: right"]
10​
[/TD]
[TD="align: right"]7
[/TD]
[TD="align: right"]12.0000%
[/TD]
[TD][/TD]
[TD="align: right"]8
[/TD]
[TD="align: right"]49.0000%
[/TD]
[TD="align: right"]9.1538
[/TD]
[TD][/TD]
[TD="align: right"]7
[/TD]
[TD="align: right"]8.3529%
[/TD]
[TD="align: right"]29.2353%
[/TD]
[TD="align: right"]6
[/TD]
[/TR]
[TR]
[TD="align: right"]
11​
[/TD]
[TD="align: right"]8
[/TD]
[TD="align: right"]20.0000%
[/TD]
[TD][/TD]
[TD="align: right"]9
[/TD]
[TD="align: right"]69.0000%
[/TD]
[TD="align: right"]10.4615
[/TD]
[TD][/TD]
[TD="align: right"]8
[/TD]
[TD="align: right"]9.1765%
[/TD]
[TD="align: right"]38.4118%
[/TD]
[TD="align: right"]7
[/TD]
[/TR]
[TR]
[TD="align: right"]
12​
[/TD]
[TD="align: right"]9
[/TD]
[TD="align: right"]18.0000%
[/TD]
[TD][/TD]
[TD="align: right"]10
[/TD]
[TD="align: right"]87.0000%
[/TD]
[TD="align: right"]11.7692
[/TD]
[TD][/TD]
[TD="align: right"]9
[/TD]
[TD="align: right"]9.1764%
[/TD]
[TD="align: right"]47.5882%
[/TD]
[TD="align: right"]7
[/TD]
[/TR]
[TR]
[TD="align: right"]
13​
[/TD]
[TD="align: right"]10
[/TD]
[TD="align: right"]9.0000%
[/TD]
[TD][/TD]
[TD="align: right"]11
[/TD]
[TD="align: right"]96.0000%
[/TD]
[TD="align: right"]13.0769
[/TD]
[TD][/TD]
[TD="align: right"]10
[/TD]
[TD="align: right"]14.3530%
[/TD]
[TD="align: right"]61.9412%
[/TD]
[TD="align: right"]8
[/TD]
[/TR]
[TR]
[TD="align: right"]
14​
[/TD]
[TD="align: right"]11
[/TD]
[TD="align: right"]2.0000%
[/TD]
[TD][/TD]
[TD="align: right"]12
[/TD]
[TD="align: right"]98.0000%
[/TD]
[TD="align: right"]14.3846
[/TD]
[TD][/TD]
[TD="align: right"]11
[/TD]
[TD="align: right"]14.4706%
[/TD]
[TD="align: right"]76.4118%
[/TD]
[TD="align: right"]9
[/TD]
[/TR]
[TR]
[TD="align: right"]
15​
[/TD]
[TD="align: right"]12
[/TD]
[TD="align: right"]1.0000%
[/TD]
[TD][/TD]
[TD="align: right"]13
[/TD]
[TD="align: right"]99.0000%
[/TD]
[TD="align: right"]15.6923
[/TD]
[TD][/TD]
[TD="align: right"]12
[/TD]
[TD="align: right"]12.1764%
[/TD]
[TD="align: right"]88.5882%
[/TD]
[TD="align: right"]10
[/TD]
[/TR]
[TR]
[TD="align: right"]
16​
[/TD]
[TD="align: right"]13
[/TD]
[TD="align: right"]1.0000%
[/TD]
[TD][/TD]
[TD="align: right"]14
[/TD]
[TD="align: right"]100.0000%
[/TD]
[TD="align: right"]17.0000
[/TD]
[TD][/TD]
[TD="align: right"]13
[/TD]
[TD="align: right"]6.8824%
[/TD]
[TD="align: right"]95.4706%
[/TD]
[TD="align: right"]10
[/TD]
[/TR]
[TR]
[TD]17
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]14
[/TD]
[TD="align: right"]1.9412%
[/TD]
[TD="align: right"]97.4118%
[/TD]
[TD="align: right"]11
[/TD]
[/TR]
[TR]
[TD]18
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]15
[/TD]
[TD="align: right"]1.0588%
[/TD]
[TD="align: right"]98.4706%
[/TD]
[TD="align: right"]12
[/TD]
[/TR]
[TR]
[TD]19
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]16
[/TD]
[TD="align: right"]0.7647%
[/TD]
[TD="align: right"]99.2353%
[/TD]
[TD="align: right"]13
[/TD]
[/TR]
[TR]
[TD]20
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]17
[/TD]
[TD="align: right"]0.7647%
[/TD]
[TD="align: right"]100.0000%
[/TD]
[TD="align: right"]14
[/TD]
[/TR]
</tbody>[/TABLE]
Code: 
E4: =E3+B4
F4: =A4*17/13
I4: =ROUND(J4-SUM($I$3:I3), 6)
J4: =IF(K4=$D$16, 1, FORECAST(H4,OFFSET($E$3,K4-1,0,2,1),OFFSET($F$3,K4-1,0,2,1)))
K4: =MATCH(H4,$F$3:$F$16)

Copy E4:F4 into E5:F16
Copy I4:K4 into I5:K20

The FORECAST formula does a linear interpolation of the cumulative segment that contains the new week number. The MATCH formula finds the low table index of the pairwise segment.
 
Last edited:
Upvote 0
joeu2004 said:
Rich (BB code): 
E4: =E3+B4
F4: =A4*17/13
I4: =ROUND(J4-SUM($I$3:I3), 6)
J4: =IF(K4=$D$16, 1, FORECAST(H4,OFFSET($E$3,K4-1,0,2,1),OFFSET($F$3,K4-1,0,2,1)))
K4: =MATCH(H4,$F$3:$F$16)

Copy E4:F4 into E5:F16
Copy I4:K4 into I5:K20
Click to expand...

KISS....
Rich (BB code): 
E4:  =E3+B4
F4:  =A4*17/13
I4:  =ROUND(J4-SUM($I$3:I3), 6)
J4:  =FORECAST(H4,OFFSET($E$3,K4-1,0,2,1),OFFSET($F$3,K4-1,0,2,1))
J20: 100%
K4:  =MATCH(H4,$F$3:$F$16)

Copy E4:F4 into E5:F16
Copy I4 into I5:I20
Copy J4:K4 into J5:K19
 
Upvote 0
Hi Joeu2004

That is an awesome piece of analysis, thanks for your time and effort.

Martin
 
Upvote 0
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