make a scatter plot the data in the table. describe the correlation of the data.   x  -4  -3    1    2    3   7                                                  ...

make a scatter plot the data in the table. describe the correlation of the data.  

x  -4  -3    1    2    3   7                                                                               y   7    4    2  -3  -4   -8

can yoy show me the calculations and graph also.

Asked on by quddoos

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embizze | High School Teacher | (Level 1) Educator Emeritus

Posted on

Plot the following points: (-4,7),(-3,4),(1,2),(2,-3),(3,-4),(7,-8)

You will not connect the points -- the graph is just the points plotted in the coordinate plane.

If you look at the points, you should notice that as you scan from left to right (the x values are increasing), that the y-values are decreasing. This indicates that there is a negative correlation between the sets of data.

Unless you are in a statistics class, the answer will be the plot of the six points and that there is a strong negative correlation.

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I do not think that you are being asked to find the actual correlation coefficient, but here it is:

Build a table with the headings `x,y,xy,x^2,y^2` ; then find the sum of each column. In summation notation find `sum x, sum y, sum xy, sum x^2, sum y^2` .

The formula for the correlation coefficient is:

`r=(n(sumxy)-(sumx)(sumy))/(sqrt([n(sumx^2)-(sumx)^2][n(sumy^2)-(sumy)^2]))`

`=(6(-112)-(6)(-2))/sqrt([6*88-36][6*158-4])`

`~~-660/681.504~~-.96845`

The correlation coefficient is approximately -.968 which is strongly negative. (The most negative correlation is -1.)

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