Originally Posted by

**Jimmy23** I'm a little confused about this homework problem. Here's the data:

patient------#of current med. problems(x)------post-op length of stay(y)

1---------------------1-------------------------------6

2---------------------2-------------------------------6

3---------------------2------------------------------11

4---------------------1-------------------------------9

5---------------------3------------------------------16

6---------------------1------------------------------16

7---------------------3-------------------------------4

8---------------------5-------------------------------8

9---------------------2------------------------------11

10--------------------3------------------------------13

After caluclating the Pearson correlation coefficient, my final answer came to be -0.085 Here's how I got that number:

[sum]Xi = 23

[sum]Yi=100

[sum]Xi^2=67

[sum]Yi^2=1156

[sum]XiYi=226

n=10

So, when I put those numbers in my formula, I get -40/468.9969

Can you have negative numbers like that? I feel like I did it all right, but that negative 40 makes me think it's wrong.