Correlation Coefficient Clarification

In summary, the correlation coefficient between X and Y is the same as the correlation coefficient between Y and X. This is because the formula for calculating the correlation coefficient is symmetric between X and Y. Therefore, swapping the values of X and Y does not affect the correlation coefficient between them.
  • #1
Tchao
7
0
Let's say that the correlation coefficient between X and Y were swapped so that the correlation coefficient between Y and X. If we were to compared the correlation coefficient between X and Y and Y and X. Based on my understanding of correlation coefficient, it doesn't matter if f X and Y were swapped. The correlation coefficient for both X and Y and Y and X would be the same.
 
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  • #2
That is correct. Correlation coefficient between the two is defined as
$$\frac{E[\ (X-E[X])(Y-E[Y])]\ }{\sqrt{E[(X-E(X))^2]E[(Y-E[Y])^2]}}$$
As you can see, this formula is symmetric between X and Y.
 

Related to Correlation Coefficient Clarification

1. What is a correlation coefficient?

A correlation coefficient is a statistical measure that indicates the strength and direction of the relationship between two variables. It is represented by the symbol "r" and ranges from -1 to 1. A value of 0 indicates no relationship, while a value of 1 or -1 indicates a perfect positive or negative relationship, respectively.

2. How is a correlation coefficient calculated?

A correlation coefficient is calculated by dividing the covariance of the two variables by the product of their standard deviations. This can also be represented by the formula r = (nΣxy - ΣxΣy) / √[(nΣx² - (Σx)²)(nΣy² - (Σy)²)], where n is the number of data points, Σ represents summation, and x and y are the two variables being analyzed.

3. What does a correlation coefficient of 0.5 mean?

A correlation coefficient of 0.5 indicates a moderate positive relationship between the two variables. This means that as one variable increases, the other variable tends to increase as well, but the relationship is not perfect. A correlation coefficient of 0.5 can also be interpreted as a 50% shared variance between the two variables.

4. Can a correlation coefficient be negative?

Yes, a correlation coefficient can be negative. This indicates a negative relationship between the two variables, meaning that as one variable increases, the other variable tends to decrease. It is important to note that a negative correlation does not necessarily mean that one variable causes the other to decrease, but rather that there is a relationship between the two.

5. Is a correlation coefficient the same as causation?

No, a correlation coefficient does not indicate causation. It only shows the relationship between two variables, but it does not prove that one variable causes the other to change. It is important to avoid assuming causation based on correlation alone and to consider other factors and potential confounding variables.

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