After reading all the posts, I think I really need some help.
I am getting different answers than everybody that has posted on here. Please tell me what I am doing wrong.
For part A
First I solve for a Ybar by taking the average of all ten Yi;s. Ybar = -0.1795
Then I solve for a TSS by subtracting the Ybar from all Yi's...squaring the ten results and then summing all ten results. TSS = 59.86964
[NEAS: The TSS is correct.]
To get the RegSS you need the fitted Y's. To get the fitted Y's you need the A, B1, & B2 (which I solve for in parts B through D). Assuming my parts B-D are correct here is how I calculated my RegSS: I used the equation Fitted Y = A + B1 * X1i + B2 * X2i. I plugged in all combinations of X1 & X2, subtracted the Ybar from all the fitted Y's, squared the results and added up all ten results. RegSS = 51.68978
[NEAS: RegSS is 52.16; RSS is 7.709.]
To get the RSS, I subtracted the RegSS from the TSS. RSS = 8.179862
To get the Rsquared I Used the equation RegSS/TSS Rsquared = 0.8633872
To get the R aka the Correlation, I take the square root for R squared. Correlation = 0.929178
[NEAS: R squared is 0.8712. the correlation needed for the standard errors is between the two independant variables, not the square root of the R sqaured.]
For Parts B-D I needed the following Variables
sum of (X1i * Yi) = 11.57
sum of (X2i * Yi) = -44.05
Sum of (X1i * X2i) = 355
Sum of X1i squared = 385
Sum of X2i squared = 385
Xbar = 5.5
Ybar = 5.5
For B1 & B2 I used the equations on the top of page 88
B1 = (11.57)(385) - (-44.05)(355)
(385)(385) - (355)(355)
B1 = 0.905054
B2 = (-44.05)(385) - (11.57)(355)
(385)(385) - (355)(355)
B2 = -0.94895
For A I also used the equation on the top of page 88
A = Ybar - B1 X1bar - B2 X2bar
-0.1795 - (0.905054)(5.5) - (-0.94895)(5.5)
A = 0.061905
What am I doing wrong?
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