Which of the following are measured by correlation coefficienta.All of the aboveb.Direction of relationship between two variables (positive or negative association)c.Linear association between two random variablesd.A unit free value for the strength of linear relationship between two random variables

The correlation coefficient measures the following:

b. Direction of relationship between two variables (positive or negative association) This means that the correlation coefficient can tell us whether there is a positive or negative relationship between two variables. A positive correlation means that as one variable increases, the other also increases. A negative correlation means that as one variable increases, the other decreases.

c. Linear association between two random variables The correlation coefficient measures the degree to which two variables move in relation to each other. If the correlation coefficient is close to +1 or -1, this indicates a strong linear relationship. If it is close to 0, this indicates a weak or no linear relationship.

d. A unit free value for the strength of linear relationship between two random variables The correlation coefficient is a unit-free measure, meaning it does not depend on the units of the variables. It only measures the strength and direction of the linear relationship.

So, the correct answer is: All of the above.