Question

Questions 2-7 will all be in regards to this data set:Observation X Y1 20 302 23 353 28 404 26 385 24 376 32 457 35 508 24 349 31 4210 23 32What is the Pearson's coefficient of correlation for the data set above?

Answer 1

Answer:

r =0.4437

Step-by-step explanation:

We have the follwoing dataset:

X: 20,23,53,4,24,32,35,24,31,23

Y: 30,35,40,38,37,45,50,34,42,32

n=10

The correlation coefficient is a "statistical measure that calculates the strength of the relationship between the relative movements of two variables". It's denoted by r and its always between -1 and 1.

And in order to calculate the correlation coefficient we can use this formula:

$r=\frac{n(\sum xy)-(\sum x)(\sum y)}{\sqrt{[n\sum x^2 -(\sum x)^2][n\sum y^2 -(\sum y)^2]}}$  

For our case we have this:

n=10 $\sum x = 269, \sum y = 383, \sum xy = 10609, \sum x^2 =8645, \sum y^2 =15007$  

Th excel figure attached shows the calculations for each sum.

$r=\frac{10(10609)-(269)(383)}{\sqrt{[10(8645) -(269)^2][10(15007) -(383)^2]}}=0.4437$  

So then the correlation coefficient would be r =0.4437