# Hockey Stick Graph Formula

• Nov 9th 2006, 07:02 PM
dontknowmuch
Hockey Stick Graph Formula
I need to come up with the (Excel) formula for a 'hockey stick' graph. Although the numbers do not really matter, here's what I need to show: time line 24 months, saturation value 12,000,000.

I hope this makes (some) sense.
• Nov 10th 2006, 08:15 AM
dontknowmuch
Guess it did not :(
• Nov 10th 2006, 09:47 AM
CaptainBlack
Quote:

Originally Posted by dontknowmuch
Guess it did not :(

Its too vague. Be more specific, and you may get some help.

RonL
• Nov 10th 2006, 09:55 AM
dontknowmuch
Let's say you start a new service and at the beginning you double your subscriber base every week then every month then every quarter and you reach saturation at about 2,000,000 subscribers within 24 months.
How would an (Excel) formula for that scenario look like?
• Nov 10th 2006, 11:29 PM
CaptainBlack
Quote:

Originally Posted by dontknowmuch
Let's say you start a new service and at the beginning you double your subscriber base every week then every month then every quarter and you reach saturation at about 2,000,000 subscribers within 24 months.
How would an (Excel) formula for that scenario look like?

You need the Verhulst equation, which has solution:

$\displaystyle S(t)=\frac{K S(0)\ e^{rt}}{K+S(0)\ (e^{rt}-1)}$

Where $\displaystyle S(0)$ is the initial number of subscribers, and $\displaystyle r$ is the initial growth constant (in your case 2/wk, so if you measure time $\displaystyle t$ in weeks has a value of 2), and $\displaystyle K$ is your saturation level.

RonL
• Nov 11th 2006, 08:36 AM
dontknowmuch
Thanks so much :D Know I just have to figure out how to put that into Excel.