I was asked to use Excel to extrapolate the growth of used capacity for
drive size on a server. Not really knowing too much about statistical
functions, I thought I'd try to educate myself.

I found the Trend function in Excel and it seemed to do what I want.
But then I was reading about the Growth Trend - where you select a
number of cells and then drag the fill handle it it just fills in
numbers for you without a specific function.

I tried both just to see what they did and I saw that the Growth Trend
produced higher estimates than the Trend function the farther out the
estimates went.

My question is which one do I trust? What is the difference between
the two?

Thanks,
Jennifer

Results from Trend function:
Date Usage
2/2/06 36537.02
2/3/06 36542.44
2/6/06 34956.7
2/15/06 38107.00
=============
Function starts here
2/16/06 37821.75941
2/17/06 38080.03568
2/18/06 38599.78576
2/19/06 38586.30352
2/20/06 38975.31669
2/21/06 39228.4507
2/22/06 39416.2162
2/23/06 39737.28979
2/24/06 39957.73951
2/25/06 40212.15911
2/26/06 40482.92078
2/27/06 40720.35541
2/28/06 40982.94612


Results from Growth Trend Dragging:
2/2/06 36537.02
2/3/06 36542.44
2/6/06 34956.70
2/15/06 38107.00
=============
Dragging starts here
2/16/06 37316.84
2/17/06 37629.26
2/18/06 37941.68
2/19/06 38254.10
2/20/06 38566.52
2/21/06 38878.94
2/22/06 39191.36
2/23/06 39503.78
2/24/06 39816.20
2/25/06 40128.62
2/26/06 40441.04
2/27/06 40753.46
2/28/06 41065.88