PDA

View Full Version : Venter Factors Question(s)

snoo
02-08-2012, 06:34 PM
Alright, I'm half embarassed to even post this but my question is under the Alternative Emergence Patterns Example where he calculates the least squares values of a and b for each column. Then he goes on to calculate the standard deviation of a and b for each column to test for significance. Would someone mind providing a sample calculation of the variance or standard deviation of a and b?

Salem127
02-08-2012, 08:31 PM
In Excel...
std dev (intercept) = INDEX(LINEST(Incremental,Cumulative,1,1),2,2)
std dev (slope) = INDEX(LINEST(Incremental,Cumulative,1,1),2,1)

For the theoretical formulas, you can google "variance of ols estimators". I also remember memorizing them as part of the Stat/Time Series VEE Course so you could look in that text if you still have it.

snoo
02-08-2012, 09:38 PM
In Excel...
std dev (intercept) = INDEX(LINEST(Incremental,Cumulative,1,1),2,2)
std dev (slope) = INDEX(LINEST(Incremental,Cumulative,1,1),2,1)

For the theoretical formulas, you can google "variance of ols estimators". I also remember memorizing them as part of the Stat/Time Series VEE Course so you could look in that text if you still have it.

Thanks! I have the excel formulas. But I'd like to see one worked out by hand. I will keep looking.

Salem127
02-08-2012, 10:16 PM
Threw this together. Hope it helps.

snoo
02-08-2012, 10:23 PM
Thanks!!!!! I will take a look!

snoo
02-15-2012, 05:51 PM
Salem127, thanks so much! There's no way I would've been able to just "remember" the formulas for the se of the slope and intercept!

Bobby
02-15-2012, 11:29 PM
I'd be very surprised if calculating the s.e. showed up on the test since it isn't in the paper.