Forecasting value of an used car in Excel

[Lucia Piepoli]

Hello,

What do you think is the best formula to calculate in Excel an extimated
value in january 1st 2008 of the used car bought new in july 1st 2004, only
having the following data of it?

(today value - new: $9900)
today's value - used car bought new in july 1st 2004: $6200
today's value - used car bought new in january 1st 2004: $5700
today's value - used car bought new in july 1st 2003: $5200

I would like to find a formula that doesn't return a negative value if I use
it for example on an extimation on 1/1/2100 instead of 1/1/2008, like the
standard forecast formula do.

Any ideas?

Thanks in advance
Luci

 

[Tom Ogilvy]

=if(formula<0,0,formula)

 

[Diego]

And what's the best "formula"?

Luci

 

[Dana DeLouis]

Not sure how this is set up, so here is just a general suggestion.
Would Excel's VDB (variable declining balance) function work for you?
What I was thinking is that you use the purchase price in this formula with
the appropriate time period to the most recent estimated value. Then, for
the Factor, point to a blank cell.
Then use Excel's goal seek to adjust the VBD's function to the most recent
value by adjusting the "factor" cell.
Then make the assumption that this "factor" is appropriate to your car's
depreciation.
Then you can use the value of this factor in all you VDB formulas.
Again, just throwing out an idea.

PS: I saw your post over in sci.math.num-analysis. One suggestion was to
simply multiply by something like 0.91 each period as a form of expediential
decay formula.

 

[Tom Ogilvy]

The one you are already using I would assume.

 

[Harlan Grove]

Tom Ogilvy wrote...

=if(formula<0,0,formula)

....

Nice, but why evaluate formula twice?

=MAX(0,formula)