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Hi Sandra,

You haven't subtracted your correction factor from the 1,946,305.5. Don't forget the correction factor is (Σy)² /N.

Hope that helps,

Professor McGuckian

Thank you!!!!

I have another quick question, for number 12 in chapter 11 homework, why is it that you subtracted the times 150-146 to find the prediction error?

The prediction error is y - ^{^}y . The variable y represents the actual y value from the original data that corresponds to the x value they are using. The ^{^}y  value is the value the regression equation you created gives you when you plug the x into the equation.

Thank you again!

Hopefully this will be my last question!

for number 62 b in the chapter 11 mixed review
62. b What is the largest deviation you might expect between any one of the 6 points and the least
squares line (find a deviation that 95% of the observed values will fall within from our line)?

you posted the answer to be 2S which stands for 2 standard deviations? Sorry if it seems obvious but just want to make sure!

Just in case, can you show me how you got the answer for 62b. I keep getting the wrong one.

Hi Sandra,

If you understood part a, then part b is easy. Part a gives us the variance, s², so we just take the square root of the answer in part a and then multiply by two. The reason we multiply by two is that we assume the error terms have a normal distribution with a mean of zero. The empirical rule from STATS I tells us that approximately 2 standard deviations capture 95% of the data under a bell curve.

Professor McGuckian