# Math Help - Please can someone help with Correlation coefficient

1. ## Please can someone help with Correlation coefficient

Hi

I am really struggling with finding the correlation coefficient for this set of data:

1991 947
1992 1098
1993 1108
1994 1107
1995 1615
1996 2282
1997 2766
1998 2505
1999 2501
2000 2637

I think I know the formula I just dont ever seem to be able to get an answer.

Thank you

2. The correlation coefficient is the ratio of the covariance over the standard deviations.
In this case it would be smart to subtract off a number like 2000 or 1990 from the first column.
If the first column are x's and the second are y's, you will need...

$\sum x_i$ and $\sum x^2_i$ and $\sum y_i$ and $\sum y^2_i$ and $\sum x_iy_i$.

3. Thank you for your help but now i am more confussed is there any way you could please break it down for me

Thank you

Originally Posted by matheagle
The correlation coefficient is the ratio of the covariance over the standard deviations.
In this case it would be smart to subtract off a number like 2000 or 1990 from the first column.
If the first column are x's and the second are y's, you will need...

$\sum x_i$ and $\sum x^2_i$ and $\sum y_i$ and $\sum y^2_i$ and $\sum x_iy_i$.

5. x= 19955
y= 18560
x2= 3.9820
y2= 3.9474

6. Originally Posted by rose
x= 19955
y= 18560
x2= 3.9820
y2= 3.9474
There's one more sum you need to calculate. Then substitute the sums into the formula given here: Computing Pearson's Correlation Coefficient

7. Originally Posted by rose
x= 19955
y= 18560
x2= 3.9820
y2= 3.9474
I think you're missing some decimal places on those sums of squares.