# Thread: Standard Error of the Forecast Formula

1. ## Standard Error of the Forecast Formula

Standard Error of the Forecast Formula

Date: May 6, 2009 12:38AM

Have you memorized this? sf^2= SEE^2[1 + 1/n + (X − Xbar)^2/(n - 1)sx^2]

Do we need to memorize this? I've been just using SEE instead of doing all that to get the exact sf.

2. Date: May 6, 2009 11:08AM

Somtimes I do that too. Use the SEE instead of sf and the prediction interval is close enough to the answer.

But I have also memorized this formula, just in case when the going gets tough.

3. Date: May 6, 2009 11:15AM

Yea, just memorize this together with the Adjusted R^2 equation. That's pretty much the only two tricky equation to remember in Quant.

4. Date: May 6, 2009 11:21AM

There was a really good shortcut for this formula last year. You may want to try to search it.

5. Date: May 6, 2009 11:49AM

r^2adj = (n-1)/(n-k-1) * (1- (1-r^2))

How did I do?

Edited 1 time(s). Last edit at Wednesday, May 6, 2009 at 11:50AM by TheAliMan.

6. Date: May 6, 2009 12:00PM

I believe the correct equation for Adjusted R^2 is

7. Date: May 6, 2009 12:01PM

isn't it 1 - (1-r^2)*(n-1)/(n-k-1). the first "1" is not included in the parenthesis.

AliMan, in your equation, the last term (1-(1-r^2)) could be expressed as (1 - 1 + r^2) = r^2, which is incorrect.

8. Date: May 6, 2009 12:46PM

mp2438, you're correct on the adjusted R^2.

9. Date: May 6, 2009 05:03PM

Thanks guys!

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df5 Re: Standard Error of the Forecast Formula

Date: May 6, 2009 05:05PM

http://www.analystforum.com/phorums/...138#msg-681138

In reference to what mwvt9 said, which is basically saying use the SEE to calculate the confidence interval, and then look for an answer that is slightly wider than the interval you calculated.

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