Exponential Growth in Stores

**mrr2** · 04-04-2013, 08:19 AM

Exponential Growth Help.xlsx

Hi all - I am confused trying to allocate new stores to a month given a range of total stores (F8), and number of months to reach the total growth (I8)

The formula I have in (O8) is =IF(O$5<$K8,0,IF(O$5=$K8,$J8,MIN(ROUND(($F8-$J8)/$I8,-1),$F8-SUM($M8:N8))))

The problem is that it doesnt consider an exponential increase in new stores over the period specified (I8), instead, it assumes a linear equal distribution of stores over a given period -

How can I have new stores come online exponetially over the period specified, so that my total number of locations over the specified period still equals the total number of stores (F8), but there is an accelaration in stores coming online?

THank you - any help would be greatly appreciated!

mr

**AndyLitch** · 04-04-2013, 08:55 AM

Is this any use ??

Stock Predictor.xls

**mrr2** · 04-04-2013, 11:40 AM

Hi Andy - thanks for looking at this for me - I looked at your workup, thanks a lot for that. How can incorporate the linest function into my formula? I think part of the problem is that I am not too familiar with arrays..

**AndyLitch** · 04-04-2013, 12:16 PM

A Non linear binomial equation takes the form Y = ax^2 + Bx + c
where a,b,c are the coefficients X is the date and Y is the stock level.

... You need at least 3 datapoints to be able to calculate the coefficients.

The a coefficients is .............. {=INDEX(LINEST(Dates,StockLevels^{1,2}),1)}
The b coefficient is................. {=INDEX(LINEST(Dates,StockLevels^{1,2}),1,2)}
The C coefficient is .................{=INDEX(LINEST(Dates,StockLevels^{1,2}),1,3)}

Where Dates is the named range of known dates and StockLevels is the named range of associated stock levels.