Econometrics

Harpy

ok so i estimated βhat = 0.25
but now i have to calculate alpha hat
the model is
Yt=alpha+betaXt+Et

t is the time thingy
and E is the error term.

am i supposed to fill beta hat into the model for beta in order to get alpha or am i supposed to do it some other completley differenent way im so confused..
what i can't figure out is what to put in for x and y in the model i've been given a datat set which i used to calculate beta hat, but don't know what numbers to use now

and another question how do i get beta by itself and not beta hat im so bad at this subject
anyone have any idea?
thanks

Harpy

ok i think i figured out the alpha and beta part
but i can't seem to get the variance of beta hat now
any one have any ideas at all?
been doing this all day but this question and another one are the only ones really giving me trouble..im just very confused with the whole beta situation

gerry87

What do the questions actually ask? What are the variables in the model on? If you've been given one dataset and run that regression you'll get one value for Beta hat. So i can't see why it would have a variance.

Just make sure its asking you for the variance of the beta, not the variance of the variable the beta is on.

Harpy

the question is:
if we assume the model is specified as follows:
Y=α +βx+e

The data set is real demand for money and real gnp, over 18 years divided into quarters.

Using the following formula
βhat =n∑XY-∑X∑Y
n∑X^2-(∑x)^2
calculate βhat and then αhat

calculate the variance of βhat

and i have to show all my workings..
i have a basic econometrics book and have been lookin through it for the last three hours with no joy..
hopefully that makes a little more sense
thanks

Flamed Diving

Harpy wrote: »

the question is:
if we assume the model is specified as follows:
Y=α +βx+e

The data set is real demand for money and real gnp, over 18 years divided into quarters.

Using the following formula
βhat =n∑XY-∑X∑Y
n∑X^2-(∑x)^2
calculate βhat and then αhat

calculate the variance of βhat

and i have to show all my workings..
i have a basic econometrics book and have been lookin through it for the last three hours with no joy..
hopefully that makes a little more sense
thanks

Off the top of my head, but isn't B0 (or ahat) just:

B0 = Ybar - BetaXbar

bar = mean

There should be a formula for the variance in your book.

Harpy

yeah i figured it out last night was just getting all confused with all the different formules but then i couldn't get the answer right..
the formula was lower case x but i just taught it was X from the model..so i was calculating using numbers from say the data set when i should of been using lower case x which was X-XBAR..
thanks lads