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Here is a bivariate data set.xy455642524351414849584645434541503546Find the correlation coefficient and report it accurate to four decimal places.r =

User Knossos
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1 Answer

7 votes

From the table, we can deduce the following:

(x, y) ==> (45, 56), (42, 52), (43, 51), (41, 48), (49, 58), (46, 45), (43, 45), (41, 50), (35, 46)

Let's find the correlation coefficient.

To find the correlation coefficient, apply the formula:


r=\frac{\Sigma(\bar{x}-x_i)(\bar{y}-y_i)}{\sqrt{\Sigma(\bar{x}-x_i)^2\Sigma(\bar{y}-y_i)^2}}

Where:

xi is the mean of the x-variables

yi is the mean of the y-variables.

Thus, we have:


\begin{gathered} x_i=(45+42+43+41+49+46+43+41+35)/(9)=(385)/(9)=42.8 \\ \\ y_i=(56+52+51+48+58+45+45+50+46)/(9)=(451)/(9)=50.1 \end{gathered}

Now, for the correlation coefficient, we have:


\begin{gathered} \Sigma(x-x_i)^2=(45-42.8)^2+(42-42.8)^2+(43-42.8)^2+(41-42.8)^2+(49-42.8)^2+(46-42.8)^2+(43-42.8)^2+(41-42.8)^2+(35-42.8)^2 \\ \Sigma(x-x_i)^2=121.6 \\ \\ \Sigma(y-y_i)^2=(56-50.1)^2+(52-50.1)^2+(51-50.1)^2+(48-50.1)^2+(58-50.1)^2+(45-50.1)^2+(45-50.1)^2+(46-50.1)^2 \\ \Sigma(y-y_i)^2=174.9 \end{gathered}

Solving further:


\begin{gathered} \Sigma(x-x_i)(y-y_1)=(45-42.8)(56-50.1)+(42-42.8)(52-50.1)+(43-42.8)(51-50.1)+(41-42.8)(48-50.1)+(49-42.8)(58-50.1)+(46-42.8)(45-50.1)+(43-42.8)(45-50.1)+(41-42.8)(50-50.1)+(35-42.8)(46-50.1) \\ \\ \Sigma(x-x_i)(y-y_i)=79.2 \end{gathered}

Now, plug in the values in the formula and solve for r.

We have:


\begin{gathered} r=(79.2)/(√((121.6)(174.9))) \\ \\ r=(79.2)/(√(21267.84)) \\ \\ r=(79.2)/(145.835) \\ \\ r=0.5433 \end{gathered}

Therefore, the correlation coefficient is 0.5433

• ANSWER:

0.5433

User JKS
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