SOLUTION: Can someone please help me figure out what I'm doing wrong? I'm trying to find the summation(d-dbar)^2 Here is the data: x y 5 6 4 5 8 6 7 10 10 6 6 11 6 5 12 8 I go

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Question 1070279: Can someone please help me figure out what I'm doing wrong?
I'm trying to find the summation(d-dbar)^2
Here is the data:
x y
5 6
4 5
8 6
7 10
10 6
6 11
6 5
12 8
I got the sum of the differences as 1
The mean of the differences (b-bar) as 0.125
Therefore, wouldn't the summation of (d-dbar)^2 be 0.765625?
The book shows the answer as 72.875.
I must be leaving out a step? I can't figure it out. Could you please help?
Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website!
you are leaving out a step.

not exactly sure what they are going, but this is what's happening if i understand what you are looking for correctly.

first of all you need to get the mean.

you did that correctly and the mean is equal to .125.

now you have to get the difference between each of the data values and the mean and then square it.

for example:

first data value is (5-6) = -1.
you would subtract the mean from that and get -1 - .125 = -1.125.
you would then square that to get 1.265625.

you would do the same for each of the values minuse the mean and then square it.

you would then sum up the squared deviations from the mean and that sum would be equal to 72.875 as the book says.

i did the calculations in excel and this is what i got.