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Free ECON141 Help (1 Viewer)
- Thread starter Grizzly
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-=«MÄLÅÇhïtÊ»=-
Gender: MALE!!!
i havent done econ141 but um..basically
Q1.
If X is N(10,4) & Y is N(25,9)
N(someting) means this random variable is distributed according to standard normal.
N(10,4) means 10 is the mean and 4 is the variance.
The expected value of X is the mean of X
So that's how he got E(X)=10 and E(Y)=25
E(2X+3Y) = 2E(X)+3E(Y) (property of expected values, no need for X and Y to be independent for this rule)
=(2*10)+(3*25) = 95
Q1.
If X is N(10,4) & Y is N(25,9)
N(someting) means this random variable is distributed according to standard normal.
N(10,4) means 10 is the mean and 4 is the variance.
The expected value of X is the mean of X
So that's how he got E(X)=10 and E(Y)=25
E(2X+3Y) = 2E(X)+3E(Y) (property of expected values, no need for X and Y to be independent for this rule)
=(2*10)+(3*25) = 95
~N(blah) means its normally distributed, not standard normal...standard normal is when the mean = 0 and standard deviation = 1-=?MČŇhﴊ?=- said:
~N(x,y) means that the mean (expected value) = x and the variance (standard deviation squared) = y
gl hf
-=«MÄLÅÇhïtÊ»=-
Gender: MALE!!!
="(...................
Oh great, thanks i get it...
And more questions for isaaq
Q. How do you calculate the standard error for an estimator ? i.e, Once you work out the b1 and b2, the estimators for beta1 and 2, how do u work out se(b1) and se(b2) ?
I know, se(b1) = root of V(b1)
But if they only give you X.t and Y.t values ?
Thanks
And more questions for isaaq
Q. How do you calculate the standard error for an estimator ? i.e, Once you work out the b1 and b2, the estimators for beta1 and 2, how do u work out se(b1) and se(b2) ?
I know, se(b1) = root of V(b1)
But if they only give you X.t and Y.t values ?
Thanks
DO it like this:
FInd what is Yhat for each correponding values of Y.The formula is Yhat t= b1+b2Xt. After that, find its residual e which is e=Y-Yhat and then find e^2.
then you need to find theta^2hat which is summation of et^2/n-2.
Finally just pluck in to the formula of V(b2)hat = theta^2hat/summation of (Xt-Mean X)^2. You can find s.e from root of the variance above.
Well for variance of b1 you need more work but the formula is
(theta^2hat*summation of Xt^2)/n*summation of (Xt-mean X)^2.then find the root of v(b1)
FInd what is Yhat for each correponding values of Y.The formula is Yhat t= b1+b2Xt. After that, find its residual e which is e=Y-Yhat and then find e^2.
then you need to find theta^2hat which is summation of et^2/n-2.
Finally just pluck in to the formula of V(b2)hat = theta^2hat/summation of (Xt-Mean X)^2. You can find s.e from root of the variance above.
Well for variance of b1 you need more work but the formula is
(theta^2hat*summation of Xt^2)/n*summation of (Xt-mean X)^2.then find the root of v(b1)
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