Forecast Basic Question

[mosh]

Hey guys,

i have a quick question regarding forecasting.

I have the following values at certain dates;

06/08/2012: 31,000
16/08/2012: 23,000
21/08/2012: 20,000

I want to forecast how long it would take to get to 10,000 and then graph it. Is there any easy way to do this?

Thanks,

 

[godsspeed]

Im not sure if this is what you're looking for.... but here's what i did

~~~All of this "MATH" can technically be skipped if you're just after a chart: if so, just skip down.~~~

Not sure if this will make sense but from 8/6/12 to 8/16/12 10 days had passed and a total of 8k units were used. Then from 6/16/12 to 8/21/12 5 days passed and 3k units were used.
So I took the total units used during the first 10 day period (8k) and dived by 2 (to establish 2 sets of 5 day periods (also known as a typical M-F work week lol)) giving an average of 4k/week. Then for an overall 'weekly' average I took the 4k and the 3k to get 3500.
So then i just created a formula to increase the last date by 5 days (i had to convert the dates to mm/dd/yy format for EXCEL to see it as a date) then created another formula that subtracted 3500 from the previous dates value. Looks like this:

(assuming the cell range from A1:B8)
Date Units
08/06/12 31000
08/16/12 23000
08/21/12 20000
08/26/12 16500
08/31/12 13000
09/05/12 9500
09/10/12 6000



MATH STINKS, I JUST WANT A CHART!!
for the chart, you can actually skip all the math that i did above (but how else are you going to confirm the chart is correct!?) I used a Column chart to plot cells (A2:B4 -- this consisted of the 3 dates you provided and their units value). Then you will want to go to (with the chart selected of course) the ChartTools ribbon --> Layout Tab --> Analysis group and you should see Trendline. Select "More Trendine Options" at the bottom of the Menu. In the dialog box that opens up, i selected Linear. then below that you'll see 'forecast'. Each period is (for some reason) see as 2 days for me, so i put 30 periods; you could do whatever time fram you'd like... Hit 'OK' and you should see a chart plotting the 3 days that you supplied and then a solid line going down (mine shows that you will reach 0 units on 09/17/12). which if you went a few more 5 day periods in our math above we would see this confirmed.


i hope this made sense and works for you!!!! best of luck