Posted by Tom on Sunday, May 26, 2013 at 12:06pm.
Does studying for an exam pay off? The number of hours studied, x, is compared with the exam grade received, y.
x 7 7 5 5 7
y 95 90 75 85 95
(a) Complete the preliminary calculations: SS(x), SS(y), and SS(xy).
Incorrect: Your answer is incorrect. . (SS(x))
Incorrect: Your answer is incorrect. . (SS(y))
Incorrect: Your answer is incorrect. . (SS(xy))
(b) Find r. (Give your answer correct to three decimal places.)
My answers were (a) 100.9, 19640 and 1396. (B) 7.04 But wrong can someone help????

Statistics  MathMate, Sunday, May 26, 2013 at 12:44pm
I do not know if we use the same terminology.
Is SS(x) sum of squares of x?
If it is, I get 197.
Would it be S(xy) instead of SS(xy), meaning just the sum of the products?
Does r mean coefficient of correlation, which has a range of 1 to 1.
If you get 7.04, perhaps you are calculating something else.

Statistics  Tom, Sunday, May 26, 2013 at 3:07pm
No it is written in book as (SS(x), so I have not ideal what to do on this one It ask for three answers in first question and 1 answer in the second part and I have missed all of it and I keep coming up with the same answers so I am not sure what I am doing on this one

Statistics  MathMate, Sunday, May 26, 2013 at 4:40pm
I was questioning SS(xy) only.
We need Sum of xy for calculating other parameters, but not sum of squares of xy.
How did you get your answers? I got 197 for SS(x). All of your answers seem to come up a little more than half of mine.

Statistics  Gayle, Sunday, May 26, 2013 at 5:35pm
197(31)squared divided by 10 197961 over 10 = 96.1 then 19796.1=100.9

Statistics  Tom, Sunday, May 26, 2013 at 5:37pm
I did the same thing that Gayle done on this for x and then y which was both wrong answers.

Statistics  MathMate, Sunday, May 26, 2013 at 8:54pm
I think you have the right formulas, but the wrong N.
N equals 5 (count either number of x values or number of y values).
So
SSx=19731²/5=4.8
SSy=39000440²/5=280
Sxy=276031*440/5=32
r=Sxy/sqrt(SSx*SSy)=0.87287
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