# Correlation - Online Test

Q1. Coefficient of correlation is also known as product moment correlation.
Explaination / Solution:

As it is the product of two different random variables.also in denominator there is product of standard deviation

Q2. If r is near to zero (i.e.) 0.1,-0.1, (or) 0.2 there is
Explaination / Solution:

As the range of correlation is 0 to 1(less to high degree correlation)

Q3. Formula for calculating correlation from the assumed mean method is
Explaination / Solution:

This is the correct formula to calculate Karl Pearson's correlation coefficient. It will take a value ranging from -1 to +1. Positive values of correlation coefficient indicate positive relationship between the two variables, while negative values are indicative of a negative relationship.

Q4. What is the range of simple correlation coefficient?
Explaination / Solution:

Because the correlation between two variables can be negative or positive or no relation

Q5. Which method of measuring correlation measures any type of relationship?
Explaination / Solution:

Only karl Pearson method shows relation between two variables and spearman correlation shows ordinal aspects of the variables

Q6. If cov(x,y) = 0 then
Explaination / Solution:

As correlation is zero, the variables are not related with each other

Q7. If D2 = 0 rank correlation is
Explaination / Solution:

If it is so then the fraction part will be zero and when zero is subtracted from1 we will get 1.

Q8. Correlation coefficient is independent of change of
Explaination / Solution:

By change of scale we mean that all values of X and y series are multiplied or divided by some constant.by change of origin we mean that a constant is subtracted from all values of x and y series if the scale and origin of X and y series are changed the value of r remain unchanged

Q9. Rank Correlation was found by
Explaination / Solution:

In 1904, Charles Edward Spearman developed the formula to calculate coefficient of correlation of qualitative variables.

Q10. The coefficient of correlation
Explaination / Solution:

Because the two series can be related directly or Inversely.